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Real Estate Properties (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 12 Months Ended | 1 Months Ended | 43 Months Ended | 10 Months Ended | 1 Months Ended | 5 Months Ended | 6 Months Ended | 1 Months Ended
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Jun. 30, 2013 | Dec. 31, 2014 property sqft building | Dec. 31, 2013 | Dec. 31, 2012 | Sep. 30, 2013 | Dec. 31, 2014 property | Aug. 31, 2013 property | May 31, 2011 property | Dec. 31, 2014 property | Oct. 31, 2014 property | Dec. 31, 2013 property | Jan. 31, 2015 property sqft | Dec. 31, 2013 property | Sep. 30, 2014 property building | Oct. 31, 2014 | Jun. 30, 2014 property item | Jan. 31, 2014 | Feb. 28, 2015 item | Jan. 31, 2013 property item | Feb. 28, 2013 property sqft | May 31, 2014 property sqft | Apr. 30, 2014 property sqft | Oct. 31, 2013 property item | Nov. 30, 2013 property item | Mar. 31, 2013 property sqft
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real estate properties, at cost |  | $ 6,238,611 us-gaap_RealEstateInvestmentPropertyAtCost | $ 5,263,625 us-gaap_RealEstateInvestmentPropertyAtCost |  |  | $ 6,238,611 us-gaap_RealEstateInvestmentPropertyAtCost |  |  | 6,238,611 us-gaap_RealEstateInvestmentPropertyAtCost |  | 5,263,625 us-gaap_RealEstateInvestmentPropertyAtCost |  | $ 5,263,625 us-gaap_RealEstateInvestmentPropertyAtCost |  |  |  |  |  |  |  |  |  |  |  |
Accumulated depreciation |  | (983,850)us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation | (840,760)us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation |  |  | (983,850)us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation |  |  | (983,850)us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation |  | (840,760)us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation |  | (840,760)us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation |  |  |  |  |  |  |  |  |  |  |  |
Assumption of mortgage notes payable |  | 15,630 us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1 | 12,266 us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1 | 121,793 us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment of asset charges recorded | 32,267 us-gaap_AssetImpairmentCharges | (10)us-gaap_AssetImpairmentCharges | 7,989 us-gaap_AssetImpairmentCharges | 3,071 us-gaap_AssetImpairmentCharges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties classified as held for sale |  | 5 snh_NumberOfRealEstatePropertiesHeldForSale |  |  |  | 5 snh_NumberOfRealEstatePropertiesHeldForSale |  |  | 5 snh_NumberOfRealEstatePropertiesHeldForSale |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of buildings classified as held for sale |  | 8 snh_NumberOfBuildingsHeldForSale |  |  |  | 8 snh_NumberOfBuildingsHeldForSale |  |  | 8 snh_NumberOfBuildingsHeldForSale |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties impaired |  | 5 snh_NumberOfRealEstatePropertiesImpaired |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain on the sale of property |  | 5,453 us-gaap_GainLossOnSaleOfProperties | 37,392 us-gaap_GainLossOnSaleOfProperties | (101)us-gaap_GainLossOnSaleOfProperties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease assets recorded |  | 577,177 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets | 166,247 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets |  |  | 577,177 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets |  |  | 577,177 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets |  | 166,247 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets |  | 166,247 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease liabilities recorded |  | 138,469 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities | 22,170 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities |  |  | 138,469 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities |  |  | 138,469 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities |  | 22,170 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities |  | 22,170 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities |  |  |  |  |  |  |  |  |  |  |  |
Reductions in rental income on capitalized above market and below market lease due to amortization |  | 2,322 snh_IncreaseDecreaseInCapitalizedAboveAndBelowMarketLeasesRentalIncome | (3,656)snh_IncreaseDecreaseInCapitalizedAboveAndBelowMarketLeasesRentalIncome | (1,597)snh_IncreaseDecreaseInCapitalizedAboveAndBelowMarketLeasesRentalIncome |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization expenses included in depreciation and amortization |  | 38,970 us-gaap_AmortizationOfIntangibleAssets | 22,718 us-gaap_AmortizationOfIntangibleAssets | 19,340 us-gaap_AmortizationOfIntangibleAssets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expenditure committed relating to leases |  | 13,883 snh_LeasesCommittedExpenditure |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Area of real estate properties leased (in square feet) |  | 750,000 snh_SquareFootageOfRealEstatePropertyLeased |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Committed but unspent tenant related obligations |  | 12,444 snh_LeaseCommittedButUnspentTenantRelatedObligations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Future minimum lease payments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2015 |  | 475,705 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent |  |  |  | 475,705 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent |  |  | 475,705 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2016 |  | 465,664 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears |  |  |  | 465,664 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears |  |  | 465,664 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2017 |  | 446,673 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears |  |  |  | 446,673 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears |  |  | 446,673 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2018 |  | 416,539 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears |  |  |  | 416,539 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears |  |  | 416,539 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2019 |  | 385,874 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears |  |  |  | 385,874 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears |  |  | 385,874 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Thereafter |  | 2,796,142 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter |  |  |  | 2,796,142 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter |  |  | 2,796,142 us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Future amortization of intangible lease assets and liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2015 |  | 39,438 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths |  |  |  | 39,438 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths |  |  | 39,438 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2016 |  | 37,037 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo |  |  |  | 37,037 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo |  |  | 37,037 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2017 |  | 33,362 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree |  |  |  | 33,362 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree |  |  | 33,362 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2018 |  | 28,668 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour |  |  |  | 28,668 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour |  |  | 28,668 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
2019 |  | 25,802 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive |  |  |  | 25,802 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive |  |  | 25,802 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Thereafter |  | 185,655 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive |  |  |  | 185,655 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive |  |  | 185,655 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Above market lease |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease assets recorded |  | 47,107 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember | 44,279 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  |  | 47,107 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  |  | 47,107 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  | 44,279 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  | 44,279 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  |  |  |  |  |  |  |  |  |  |  |
Accumulated amortization on lease assets |  | 22,749 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember | 16,148 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  |  | 22,749 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  |  | 22,749 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  | 16,148 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  | 16,148 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceAboveMarketMember |  |  |  |  |  |  |  |  |  |  |  |
Weighted average amortization period |  | 5 years 3 months 18 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
In-place lease intangibles |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease assets recorded |  | 530,070 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember | 121,968 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  |  | 530,070 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  |  | 530,070 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  | 121,968 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  | 121,968 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  |  |  |  |  |  |  |  |  |  |  |
Accumulated amortization on lease assets |  | 81,640 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember | 46,605 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  |  | 81,640 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  |  | 81,640 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  | 46,605 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  | 46,605 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_LeasesAcquiredInPlaceMember |  |  |  |  |  |  |  |  |  |  |  |
Weighted average amortization period |  | 12 years 9 months 18 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Below market lease |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated amortization on lease assets |  | 15,643 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceBelowMarketMember | 9,642 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceBelowMarketMember |  |  | 15,643 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceBelowMarketMember |  |  | 15,643 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceBelowMarketMember |  | 9,642 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceBelowMarketMember |  | 9,642 us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = snh_LeasesAcquiredInPlaceBelowMarketMember |  |  |  |  |  |  |  |  |  |  |  |
Weighted average amortization period |  | 13 years 4 months 24 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Five Star |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real estate improvements purchased |  | 25,804 snh_RealEstateImprovementsByLesseePurchased / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember | 27,208 snh_RealEstateImprovementsByLesseePurchased / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember | 30,520 snh_RealEstateImprovementsByLesseePurchased / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase or decrease in annual lease rent payable |  | 2,066 snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember | 2,177 snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember | 2,456 snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember | (9,500)snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties classified as held for sale |  | 1 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember | 4 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  | 1 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  | 1 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  | 4 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  | 4 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  |  |  |  |  |  |  |  |  |  |
Number of buildings classified as held for sale |  | 7 snh_NumberOfBuildingsHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember | 7 snh_NumberOfBuildingsHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  | 7 snh_NumberOfBuildingsHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  | 7 snh_NumberOfBuildingsHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  | 7 snh_NumberOfBuildingsHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  | 7 snh_NumberOfBuildingsHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  |  |  |  |  |  |  |  |  |  |
Property held for sale (in square feet) |  | 323,541 snh_AreaOfRealEstatePropertyHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember | 831,499 snh_AreaOfRealEstatePropertyHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  | 323,541 snh_AreaOfRealEstatePropertyHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  | 323,541 snh_AreaOfRealEstatePropertyHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  | 831,499 snh_AreaOfRealEstatePropertyHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  | 831,499 snh_AreaOfRealEstatePropertyHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  |  |  |  |  |  |  |  |  |  |
Number of properties impaired |  | 4 snh_NumberOfRealEstatePropertiesImpaired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior living communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  | 312 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember | 744 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  | 312 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  | 312 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  | 744 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  | 744 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  |  |  |  |  |  |  |  |  |  |
Impairment of asset charges recorded |  | 4,377 us-gaap_AssetImpairmentCharges / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember | 1,304 us-gaap_AssetImpairmentCharges / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties classified as held for sale |  | 4 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember | 10 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  | 4 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  | 4 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  | 10 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  | 10 snh_NumberOfRealEstatePropertiesHeldForSale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  |  |  |  |  |  |  |  |  |  |
Real estate properties, held for sale |  | 3,551 us-gaap_RealEstateHeldforsale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember | 27,888 us-gaap_RealEstateHeldforsale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  | 3,551 us-gaap_RealEstateHeldforsale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  | 3,551 us-gaap_RealEstateHeldforsale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  | 27,888 us-gaap_RealEstateHeldforsale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  | 27,888 us-gaap_RealEstateHeldforsale / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember |  |  |  |  |  |  |  |  |  |  |  |
Senior living communities | Five Star |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  | 46 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  |  |  | 2 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  | 6 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember | 36 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired, referred to as managed properties |  | 46 snh_NumberOfPropertiesAcquiredManagedProperties / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  | 47,430 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  |  |  |  |  | 1 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase or decrease in annual lease rent payable |  |  |  |  |  |  | (255)snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Skilled nursing facilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  |  |  |  |  |  |  |  | 3 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SkilledNursingFacilityMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assisted living facility member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  |  |  |  |  |  |  |  | 3 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_AssistedLivingFacilityMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rehabilitation hospitals | Five Star |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  |  |  |  |  |  |  |  |  | 2 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_RehabilitationHospitalsMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisition | Triple Net Leased Net Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  |  | 150 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  | 150 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 150 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  | 22,350 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assumption of mortgage notes payable |  |  | 12,266 us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Premium on Assumed Debt |  |  | 1,040 snh_NoncashOrPartNoncashAcquisitionPremiumOnDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets recorded related to acquisition |  |  | 1,039 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  | 1,039 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 1,039 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |
Acquisition | Triple Net Leased Net Senior Living Communities | Stellar Senior Living, LLC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Annual lease rent payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,732 us-gaap_AccruedRentCurrentAndNoncurrent / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_StellarSeniorLivingLLCMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |
Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  | 2 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 5 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  | 228 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 374 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  | 228 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 93 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 228 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 374 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 374 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  | 47,430 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 62,999 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  | 22,030 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets recorded related to acquisition |  | 3,119 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 4,075 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  | 3,119 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 1,013 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 3,119 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 4,075 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 4,075 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |
Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  | 2 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 6 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of buildings acquired |  | 3 snh_NumberOfBuildingsAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 7 snh_NumberOfBuildingsAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  | 1,156,963 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 117,475 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assumption of mortgage notes payable |  | 15,630 us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Area of real estate properties (in square feet) |  | 1,776,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 385,171,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  | 1,776,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  | 1,776,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 385,171,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 385,171,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |
Premium on Assumed Debt |  | 1,013 snh_NoncashOrPartNoncashAcquisitionPremiumOnDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease assets recorded |  | 411,021 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 10,012 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  | 411,021 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  | 411,021 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 10,012 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 10,012 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease liabilities recorded |  | 118,495 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 2,271 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  | 118,495 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  | 118,495 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 2,271 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  | 2,271 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |
Acquisition | MOBs | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  | 23 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |  |  |  | 23 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |  |  |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  |  |  |  |  |  |  | 539,000 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |  |  |  |  |  |  |
Assumption of mortgage notes payable |  |  |  |  |  |  |  |  |  |  |  | 30,000 us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |  |  |  |  |  |  |
Area of real estate properties (in square feet) |  |  |  |  |  |  |  |  |  |  |  | 2,200,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisition | Senior living communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  | 2 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 6 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  |  |  |  |  |  |  |  | 6 snh_NumberOfPropertiesSold / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  | 3 snh_NumberOfPropertiesSold / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  |  |  |  |  |  | 15,650 snh_RealEstateAggregateSalesPrice / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  | 92,550 snh_RealEstateAggregateSalesPrice / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |  |
Gain on the sale of property |  |  |  |  |  |  |  |  |  | 5,452 us-gaap_GainLossOnSaleOfProperties / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  | 37,392 us-gaap_GainLossOnSaleOfProperties / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |  |
Sale | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  | 3 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |  | 3 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |
Number of buildings sold |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 snh_NumberOfBuildingsSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,675 snh_RealEstateAggregateSalesPrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |
Gain on the sale of property |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 us-gaap_GainLossOnSaleOfProperties / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |
Sale | Senior living communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  | 6 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale | Senior living communities | Five Star |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  |  |  |  |  |  | 112 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  | 156 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  |  |  | 2,550 snh_RealEstateAggregateSalesPrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  | 4,500 snh_RealEstateAggregateSalesPrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |
Increase or decrease in annual lease rent payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 285 snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember | (452)snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember | 210 snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |
Sale | Senior living communities | Five Star | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 120 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 250 snh_RealEstateAggregateSalesPrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |
Increase or decrease in annual lease rent payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (23)snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |
Sale | Skilled nursing facilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  |  |  |  |  |  |  |  |  |  |  | 1 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SkilledNursingFacilityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |  |
Sale | Rehabilitation hospitals |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  | 2 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_RehabilitationHospitalsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  | 2 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_RehabilitationHospitalsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |  |
Gain on the sale of property |  |  | 36,251 us-gaap_GainLossOnSaleOfProperties / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_RehabilitationHospitalsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Properties acquired in 2014 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease assets recorded |  | 414,140 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2014Member |  |  |  | 414,140 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2014Member |  |  | 414,140 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2014Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease liabilities recorded |  | 118,495 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2014Member |  |  |  | 118,495 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2014Member |  |  | 118,495 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2014Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Properties acquired in 2013 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease assets recorded |  |  | 17,131 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2013Member |  |  |  |  |  |  |  | 17,131 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2013Member |  | 17,131 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2013Member |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease liabilities recorded |  |  | 2,271 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2013Member |  |  |  |  |  |  |  | 2,271 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2013Member |  | 2,271 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_RealEstateAcquisition2013Member |  |  |  |  |  |  |  |  |  |  |  |
Agreement to acquire | Senior living communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of communities |  |  |  |  |  | 38 snh_NumberOfCommunities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  | 3,466 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  | 3,466 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  | 3,466 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of states in which property is located |  | 16 snh_NumberOfStatesInWhichProertyIsLocated / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  | 16 snh_NumberOfStatesInWhichProertyIsLocated / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  | 16 snh_NumberOfStatesInWhichProertyIsLocated / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  | 790,000 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assumption of mortgage notes payable |  |  |  |  |  | 153,000 us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average interest rate on debt (as a percent) |  |  |  |  |  | 4.80%snh_DebtWeightedAverageInterestRateDuringThePeriod / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreement to acquire | Senior living communities | Leasing Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of communities |  |  |  |  |  | 18 snh_NumberOfCommunities / us-gaap_LeaseArrangementTypeAxis = snh_LeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  | 1,847 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_LeaseArrangementTypeAxis = snh_LeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  | 1,847 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_LeaseArrangementTypeAxis = snh_LeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  | 1,847 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_LeaseArrangementTypeAxis = snh_LeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of operators |  |  |  |  |  | 6 snh_NumberOfOperators / us-gaap_LeaseArrangementTypeAxis = snh_LeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of operators currently tenants of the entity |  |  |  |  |  | 0 snh_NumberOfOperatorsCurrentlyTenantsOfEntity / us-gaap_LeaseArrangementTypeAxis = snh_LeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Agreement to acquire | Senior living communities | Non Leasing Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of communities |  |  |  |  |  | 20 snh_NumberOfCommunities / us-gaap_LeaseArrangementTypeAxis = snh_NonLeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  | 1,619 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_LeaseArrangementTypeAxis = snh_NonLeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  | 1,619 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_LeaseArrangementTypeAxis = snh_NonLeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  | 1,619 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_LeaseArrangementTypeAxis = snh_NonLeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of operators |  |  |  |  |  | 6 snh_NumberOfOperators / us-gaap_LeaseArrangementTypeAxis = snh_NonLeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of operators currently property managers under the entity |  |  |  |  |  | 0 snh_NumberOfOperatorsCurrentlyPropertyManagersOfEntity / us-gaap_LeaseArrangementTypeAxis = snh_NonLeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of leasing managers in group of non leasing operators |  |  |  |  |  | 1 snh_NumberOfLeasingManagersInGroupOfNonLeasingOperators / us-gaap_LeaseArrangementTypeAxis = snh_NonLeasingMember / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AgreementToAcquireMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Land |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real estate properties, at cost |  | 683,979 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember | 623,756 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember |  |  | 683,979 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember |  |  | 683,979 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember |  | 623,756 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember |  | 623,756 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember |  |  |  |  |  |  |  |  |  |  |  |
Land | Acquisition | Triple Net Leased Net Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  | 5,120 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Land | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  | 2,803 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 5,155 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  | 1,548 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Land | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  | 55,784 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 13,899 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Buildings and improvements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real estate properties, at cost |  | 5,318,178 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember | 4,423,517 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  |  | 5,318,178 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  |  | 5,318,178 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  | 4,423,517 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  | 4,423,517 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  |  |  |  |  |  |  |  |  |  |  |
Accumulated depreciation |  | 848,605 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember | 723,258 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  |  | 848,605 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  |  | 848,605 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  | 723,258 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  | 723,258 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember |  |  |  |  |  |  |  |  |  |  |  |
Buildings and improvements | Acquisition | Triple Net Leased Net Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  | 16,562 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Buildings and improvements | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  | 40,819 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 52,155 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  | 18,666 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Buildings and improvements | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  | 809,666 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 95,835 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Furniture, fixtures and equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real estate properties, at cost |  | 236,454 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember | 216,352 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  |  | 236,454 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  |  | 236,454 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  | 216,352 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  | 216,352 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  |  |  |  |  |  |  |  |  |  |  |
Accumulated depreciation |  | 135,245 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember | 117,502 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  |  | 135,245 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  |  | 135,245 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  | 117,502 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  | 117,502 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember |  |  |  |  |  |  |  |  |  |  |  |
Furniture, fixtures and equipment | Acquisition | Triple Net Leased Net Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  | 669 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Furniture, fixtures and equipment | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  | 689 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember | 1,614 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  | 803 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
WA | Acquisition | Triple Net Leased Net Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |  |
Number of living units |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 150 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 22,350 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |  |
Assumption of mortgage notes payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12,266 us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |  |
Premium on Assumed Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,040 snh_NoncashOrPartNoncashAcquisitionPremiumOnDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |  |
Intangible assets recorded related to acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,039 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |  |
WA | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 38,000 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |
Area of real estate properties (in square feet) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 145,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |
Intangible lease assets recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,736 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |
Intangible lease liabilities recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,588 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |
WA | Land | Acquisition | Triple Net Leased Net Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,120 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |  |
WA | Land | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,639 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |
WA | Buildings and improvements | Acquisition | Triple Net Leased Net Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 16,562 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |  |
WA | Buildings and improvements | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 27,213 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |
WA | Furniture, fixtures and equipment | Acquisition | Triple Net Leased Net Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 669 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_TripleNetSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WA |  |  |  |  |  |
MA | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  |  |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  |  | 49,500 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,124,031 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |
Area of real estate properties (in square feet) |  |  |  |  |  |  | 105,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,651,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |
Intangible lease assets recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 403,349 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |
Intangible lease liabilities recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 118,485 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |
MA | Land | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  | 4,559 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |  |  |  |  |  |  |  |  |  |  | 52,643 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |
MA | Buildings and improvements | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  | 44,941 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |  |  |  |  |  |  |  |  |  |  | 786,524 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MA |  |  |  |
Texas | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 32,932 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |
Assumption of mortgage notes payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15,630 us-gaap_NoncashOrPartNoncashAcquisitionDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |
Area of real estate properties (in square feet) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 125,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |
Premium on Assumed Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,013 snh_NoncashOrPartNoncashAcquisitionPremiumOnDebtAssumed1 / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |
Intangible lease assets recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,672 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |
Intangible lease liabilities recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |
Texas | Sale | Senior living communities | Five Star |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 36 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |  |  |  |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,400 snh_RealEstateAggregateSalesPrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |  |  |  |  |  |
Texas | Land | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,141 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |
Texas | Buildings and improvements | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 23,142 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_TX |  |  |
Virginia | Sale | Senior living communities | Five Star |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  |  |  |  |  |  |  |  |  | 70 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_VA |  |  |  |  | 70 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_VA |  |  |  |  |  |  |  |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,850 snh_RealEstateAggregateSalesPrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_VA |  |  |  |  |  |  |  |  |  |
Arizona | Sale | Senior living communities | Five Star |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  |  |  |  |  |  |  |  |  | 177 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_AZ |  |  |  |  | 177 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_AZ |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_AZ |  |  |  |  |  |  |  |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,900 snh_RealEstateAggregateSalesPrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_AZ |  |  |  |  |  |  |  |  |  |
Increase or decrease in annual lease rent payable |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (590)snh_IncreaseDecreaseOperatingLeasesAnnualRent / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_RelatedPartyTransactionsByRelatedPartyAxis = snh_FiveStarQualityCareIncMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_SaleOfAssetsMember / us-gaap_StatementGeographicalAxis = stpr_AZ |  |  |  |  |  |  |  |  |  |
Various | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = snh_VariousMember |  |
Number of living units |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 213 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = snh_VariousMember |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 29,004 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = snh_VariousMember |  |
Intangible assets recorded related to acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,289 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = snh_VariousMember |  |
Various | Land | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,242 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = snh_VariousMember |  |
Various | Buildings and improvements | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 23,861 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = snh_VariousMember |  |
Various | Furniture, fixtures and equipment | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 612 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = snh_VariousMember |  |
WI | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |
Number of living units |  | 52 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  | 52 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  | 52 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 68 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  | 7,000 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,965 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |
Intangible assets recorded related to acquisition |  | 849 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  | 849 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  | 849 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 773 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |
WI | Additional acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of living units |  | 176 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  | 176 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  | 176 us-gaap_NumberOfUnitsInRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  | 40,430 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Intangible assets recorded related to acquisition |  | 2,270 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  | 2,270 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  | 2,270 snh_RealEstatePropertiesAcquiredIntangibleAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
WI | Land | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  | 188 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,365 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |
WI | Land | Additional acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  | 2,615 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
WI | Buildings and improvements | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  | 5,862 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9,628 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |
WI | Buildings and improvements | Additional acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  | 34,957 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
WI | Furniture, fixtures and equipment | Acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  | 101 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 199 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |
WI | Furniture, fixtures and equipment | Additional acquisition | Managed Senior Living Communities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  | 588 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_ManagedSeniorLivingCommunitiesMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = snh_FurnitureFixturesAndEquipmentMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = snh_AdditionalSeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_WI |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PENNSYLVANIA | Senior living communities | Subsequent event |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties to be sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 snh_NumberOfPropertiesSold / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_StatementGeographicalAxis = stpr_PA / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |
Sale price of property sold and agreed to be sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 250 snh_RealEstateAggregateSalesPrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_SeniorLivingCommunityMember / us-gaap_StatementGeographicalAxis = stpr_PA / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |
MS | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MS
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 14,600 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MS
Area of real estate properties (in square feet) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 72,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MS
Intangible lease assets recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,498 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MS
Intangible lease liabilities recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 683 snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MS
MS | Land | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,269 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MS
MS | Buildings and improvements | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12,516 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_MS
FL | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties acquired or agreed to be acquired |  |  |  |  |  |  |  |  |  |  | 3 snh_NumberOfPropertiesAcquired / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash Paid plus Assumed Debt, excluding closing costs |  |  |  |  |  |  |  |  |  |  | 15,375 snh_RealEstateAggregatePurchasePrice / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  |  |  |  |  |  |  |  |  |  |  |  |  |
Area of real estate properties (in square feet) |  |  | 63,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  |  |  |  |  |  |  | 63,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  | 63,000 us-gaap_AreaOfRealEstateProperty / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  |  |  |  |  |  |  |  |  |  |  |
Intangible lease assets recorded |  |  | 1,778 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  |  |  |  |  |  |  | 1,778 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  | 1,778 snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  |  |  |  |  |  |  |  |  |  |  |
FL | Land | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  | 2,432 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  |  |  |  |  |  |  |  |  |  |  |  |  |
FL | Buildings and improvements | Acquisition | MOBs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Real Estate Properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property plant and equipment recorded |  |  |  |  |  |  |  |  |  |  | 11,165 snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment / us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis = snh_MedicalOfficeBuildingMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingImprovementsMember / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember / us-gaap_StatementGeographicalAxis = stpr_FL |  |  |  |  |  |  |  |  |  |  |  |  |  |

X
- Definition Represents the area of a real estate property, held for sale. + References No definition available. + Details
Name: | snh_AreaOfRealEstatePropertyHeldForSale
Namespace Prefix: | snh_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average interest rate on debt during the period. + References No definition available. + Details
Name: | snh_DebtWeightedAverageInterestRateDuringThePeriod
Namespace Prefix: | snh_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | snh_FiniteLivedIntangibleLeaseAssetsAndLiabilitiesFutureAmortizationExpenseAbstract
Namespace Prefix: | snh_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the increase or decrease in rental income associated with capitalized above market and below market lease due to amortization. + References No definition available. + Details
Name: | snh_IncreaseDecreaseInCapitalizedAboveAndBelowMarketLeasesRentalIncome
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the increase or decrease on the annual rent the lessee is obligated to pay on an operating lease. + References No definition available. + Details
Name: | snh_IncreaseDecreaseOperatingLeasesAnnualRent
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of committed but unspent tenant related obligations based on executed lease. + References No definition available. + Details
Name: | snh_LeaseCommittedButUnspentTenantRelatedObligations
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the amount of expenditure committed by entity relating to leases. + References No definition available. + Details
Name: | snh_LeasesCommittedExpenditure
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of premium on assumed debt that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. + References No definition available. + Details
Name: | snh_NoncashOrPartNoncashAcquisitionPremiumOnDebtAssumed1
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This element represents the number of buildings acquired or agreed to be acquired by the entity during the period. + References No definition available. + Details
Name: | snh_NumberOfBuildingsAcquired
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of buildings owned by the entity, which are classified as held for sale as of the balance sheet date. + References No definition available. + Details
Name: | snh_NumberOfBuildingsHeldForSale
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition This element represents the number of buildings sold by the entity. + References No definition available. + Details
Name: | snh_NumberOfBuildingsSold
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of communities. + References No definition available. + Details
Name: | snh_NumberOfCommunities
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of managers with a leasing arrangement through the entity that are part of the group of non leasing operators. + References No definition available. + Details
Name: | snh_NumberOfLeasingManagersInGroupOfNonLeasingOperators
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of operators or property managers. + References No definition available. + Details
Name: | snh_NumberOfOperators
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of operators currently property managers under the entity. + References No definition available. + Details
Name: | snh_NumberOfOperatorsCurrentlyPropertyManagersOfEntity
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of operators currently having a lease arrangement with the entity. + References No definition available. + Details
Name: | snh_NumberOfOperatorsCurrentlyTenantsOfEntity
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition This element represents the number of properties acquired or agreed to be acquired by the entity during the period. + References No definition available. + Details
Name: | snh_NumberOfPropertiesAcquired
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of properties acquired or agreed to be acquired by the entity during the period, which are referred by the entity as managed properties. + References No definition available. + Details
Name: | snh_NumberOfPropertiesAcquiredManagedProperties
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition This element represents the number of properties sold or agreed to be sold by the entity. + References No definition available. + Details
Name: | snh_NumberOfPropertiesSold
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of real estate properties owned by the entity, which are classified as held for sale as of the balance sheet date. + References No definition available. + Details
Name: | snh_NumberOfRealEstatePropertiesHeldForSale
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the number of real estate properties impaired. + References No definition available. + Details
Name: | snh_NumberOfRealEstatePropertiesImpaired
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of states in which the comapnies property is located. + References No definition available. + Details
Name: | snh_NumberOfStatesInWhichProertyIsLocated
Namespace Prefix: | snh_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition This element represents the aggregate purchase price excluding closing costs, of real estate properties acquired by the entity during the period. + References No definition available. + Details
Name: | snh_RealEstateAggregatePurchasePrice
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This element represents the aggregate sales price excluding closing costs, of real estate properties sold by the entity during the period. + References No definition available. + Details
Name: | snh_RealEstateAggregateSalesPrice
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the amount of improvements to real estate properties made by lessees and purchased by the entity. + References No definition available. + Details
Name: | snh_RealEstateImprovementsByLesseePurchased
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the intangible assets recorded as part of the real estate acquisition. + References No definition available. + Details
Name: | snh_RealEstatePropertiesAcquiredIntangibleAssets
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents the intangible lease assets recorded as part of the real estate acquisition. + References No definition available. + Details
Name: | snh_RealEstatePropertiesAcquiredIntangibleLeaseAssets
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents the intangible lease liabilities recorded as part of the real estate acquisition. + References No definition available. + Details
Name: | snh_RealEstatePropertiesAcquiredIntangibleLeaseLiabilities
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the property plant and equipment assets recorded as part of the real estate acquisition. + References No definition available. + Details
Name: | snh_RealEstatePropertiesAcquiredPropertyPlantAndEquipment
Namespace Prefix: | snh_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the area of the real estate property subject to an operating lease. + References No definition available. + Details
Name: | snh_SquareFootageOfRealEstatePropertyLeased
Namespace Prefix: | snh_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | duration

X
- Definition Carrying value as of the balance sheet date of obligations incurred through that date and payable for contractual rent under lease arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.15(5)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 15 -Subparagraph a -Article 7 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 15 -Subparagraph 5 -Article 9 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.15(5)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_AccruedRentCurrentAndNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
Name: | us-gaap_AmortizationOfIntangibleAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Area of a real estate property. + References No definition available. + Details
Name: | us-gaap_AreaOfRealEstateProperty
Namespace Prefix: | us-gaap_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2420-110228 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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Balance Type: | debit
Period Type: | instant

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- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 + Details
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- Definition The amount of debt that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586 + Details
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- Definition The number of units in a real estate property owned as of the balance sheet date. + References No definition available. + Details
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- Definition Future rental payments receivable within one year of the balance sheet date under an operating lease. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718 + Details
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- Definition Future rental payments receivable within the fifth year from the balance sheet date under an operating lease. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718 + Details
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- Definition Future rental payments receivable within the fourth year from the balance sheet date under an operating lease. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718 + Details
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- Definition Future rental payments receivable within the third year from the balance sheet date under an operating lease. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718 + Details
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- Definition Future rental payments receivable within the second year from the balance sheet date under an operating lease. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718 + Details
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- Definition Future minimum lease payments receivable under operating leases for periods greater than five years following the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718 + Details
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- Definition Carrying amount as of the balance sheet date of investments in land and buildings held for sale, excluding real estate considered to be inventory of the entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(f)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition The cumulative amount of depreciation for real estate property held for investment purposes. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(3)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Article 7 + Details
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- Definition Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(d)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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