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Real Estate Properties - Narrative (Details)		1 Months Ended																						3 Months Ended	12 Months Ended
	Jun. 29, 2016 pooling_agreement	Feb. 28, 2019 USD ($) community	Dec. 31, 2018 USD ($) ft² state living_unit community property	Jun. 30, 2018 USD ($) living_unit community nursing_facility	May 31, 2018 USD ($) community	Mar. 31, 2018 USD ($) ft² building community property	Feb. 28, 2018 USD ($) living_unit community	Jan. 31, 2018 USD ($) ft² living_unit building community property	Dec. 31, 2017 USD ($) ft² living_unit building community property	Nov. 30, 2017 USD ($) ft² building property	Oct. 31, 2017 USD ($) ft² building property	Aug. 31, 2017 USD ($)	Jul. 31, 2017 USD ($) ft² building property	Jan. 31, 2017 USD ($) ft² building property	Dec. 31, 2016 USD ($) ft² living_unit community property	Oct. 31, 2016 USD ($) ft² building property	Sep. 30, 2016 USD ($)	Jul. 31, 2016 USD ($) building property	Jun. 30, 2016 USD ($) state living_unit property pooling_agreement lease_agreement	May 31, 2016 USD ($) ft² living_unit building community property	Apr. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Feb. 29, 2016 USD ($) ft² building property	Jun. 30, 2017 USD ($)	Dec. 31, 2018 USD ($) ft² state living_unit building community property	Dec. 31, 2017 USD ($) ft² property	Dec. 31, 2016 USD ($) ft² living_unit parcel building community property	Nov. 30, 2018 living_unit
Real Estate Properties
Acquired real estate leases			$ 691,219,000						$ 791,067,000																$ 691,219,000	$ 791,067,000
Net Book Value of Collateral			6,341,908,000						6,370,286,000																6,341,908,000	6,370,286,000
Real estate property - accumulated depreciation			1,534,392,000						1,454,477,000																1,534,392,000	1,454,477,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019			579,757,000																						579,757,000
2020			552,947,000																						552,947,000
2021			528,448,000																						528,448,000
2022			507,667,000																						507,667,000
2023			483,525,000																						483,525,000
Thereafter			$ 1,844,178,000																						$ 1,844,178,000
Area of real estate properties (in square feet) | ft²			812,000																						812,000
Mortgage debt assumed																									$ 44,386,000	0	$ 0
Number of states in which properties are located | state			42																						42
Acquired real estate lease obligations			$ 134,395,000						136,713,000																$ 134,395,000	136,713,000
Accumulated amortization of capitalized below market lease values			48,091,000						40,695,000																48,091,000	40,695,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2019			57,515,000																						57,515,000
2020			43,896,000																						43,896,000
2021			39,410,000																						39,410,000
2022			36,583,000																						36,583,000
2023			35,089,000																						35,089,000
Thereafter			120,447,000																						120,447,000
Impairment of assets																									66,346,000	5,082,000	18,674,000
Gain on sale of properties																									261,916,000	46,055,000	$ 4,061,000
Lease committed but unspent tenant related obligations																									22,009,000	20,681,000
Land
Real Estate Properties
Net Book Value of Collateral			844,567,000						824,879,000																844,567,000	824,879,000
Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral			7,031,733,000						6,999,884,000																7,031,733,000	6,999,884,000
Building
Real Estate Properties
Real estate property - accumulated depreciation			1,408,793,000						1,250,057,000																1,408,793,000	1,250,057,000
Building Improvements
Real Estate Properties
Real estate property - accumulated depreciation			125,599,000						204,420,000																$ 125,599,000	204,420,000
MOBs
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property																									13		2
Number of buildings acquired | building																									13		5
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Impairment of assets																									$ 46,797,000		$ 11,488,000
Leases committed expenditure																									$ 17,212,000	$ 22,540,000
Area of real estate properties leased (in square feet) | ft²																									881,502	1,300,000
MOBs | Acquisitions
Real Estate Properties
Acquired real estate leases			$ 29,527,000						$ 27,713,000						$ 9,645,000										$ 29,527,000	$ 27,713,000	$ 9,645,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property																									4	6	3
Area of real estate properties (in square feet) | ft²			535,000						630,000						390,000										535,000	630,000	390,000
Purchase price, including closing costs																									$ 114,973,000	$ 113,168,000
Mortgage debt assumed																									11,050,000	0	$ 0
Purchase price excluding closing costs																											86,432,000
Acquired real estate lease obligations			$ 0						$ 20,000						$ 1,091,000										0	20,000	1,091,000
MOBs | Acquisitions | Land
Real Estate Properties
Net Book Value of Collateral			19,736,000						25,618,000						7,845,000										19,736,000	25,618,000	7,845,000
MOBs | Acquisitions | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral			65,710,000						59,857,000						$ 70,033,000										$ 65,710,000	59,857,000	70,033,000
MOBs | Acquisitions | 3 States
Real Estate Properties
Acquired real estate leases								$ 20,220,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property								3
Number of buildings acquired | building								3
Area of real estate properties (in square feet) | ft²								400,000
Purchase price, including closing costs								$ 91,698,000
Acquisition costs incurred								$ 544,000
Weighted average amortization period								5 years 3 months 18 days
Mortgage debt assumed								$ 0
Acquired real estate lease obligations								0
MOBs | Acquisitions | 3 States | Land
Real Estate Properties
Net Book Value of Collateral								16,873,000
MOBs | Acquisitions | 3 States | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral								$ 54,605,000
MOBs | Acquisitions | Virginia
Real Estate Properties
Acquired real estate leases						$ 9,307,000			$ 4,986,000																	$ 4,986,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property						1			1
Number of buildings acquired | building						1			1
Area of real estate properties (in square feet) | ft²						135,000			136,000																	136,000
Purchase price, including closing costs						$ 23,275,000			$ 15,844,000
Acquisition costs incurred						$ 525,000			$ 275,000
Weighted average amortization period						5 years 9 months 18 days			7 years 2 months 12 days
Above market, acquired lease amortization period									6 years 1 month 6 days
Below market, acquired lease amortization period									6 years 9 months 18 days
Mortgage debt assumed						$ 11,050,000			$ 0
Acquired real estate lease obligations						0			20,000																	$ 20,000
MOBs | Acquisitions | Virginia | Land
Real Estate Properties
Net Book Value of Collateral						2,863,000			3,263,000																	3,263,000
MOBs | Acquisitions | Virginia | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral						11,105,000			7,615,000																	7,615,000
MOBs | Acquisitions | Kansas
Real Estate Properties
Acquired real estate leases														$ 6,338,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property														1
Number of buildings acquired | building														1
Area of real estate properties (in square feet) | ft²														117,000
Purchase price, including closing costs														$ 15,106,000
Acquisition costs incurred														$ 35,000
Weighted average amortization period														10 years 3 months 19 days
Mortgage debt assumed														$ 0
Acquired real estate lease obligations														0
MOBs | Acquisitions | Kansas | Land
Real Estate Properties
Net Book Value of Collateral														1,522,000
MOBs | Acquisitions | Kansas | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral														$ 7,246,000
MOBs | Acquisitions | Maryland
Real Estate Properties
Acquired real estate leases													$ 3,937,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property													1
Number of buildings acquired | building													1
Area of real estate properties (in square feet) | ft²													59,000
Purchase price, including closing costs													$ 16,601,000
Acquisition costs incurred													$ 383,000
Weighted average amortization period													3 years 9 months 18 days
Mortgage debt assumed													$ 0
Acquired real estate lease obligations													0
MOBs | Acquisitions | Maryland | Land
Real Estate Properties
Net Book Value of Collateral													6,138,000
MOBs | Acquisitions | Maryland | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral													$ 6,526,000
MOBs | Acquisitions | 2 States
Real Estate Properties
Acquired real estate leases											$ 7,016,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property											2
Number of buildings acquired | building											2
Area of real estate properties (in square feet) | ft²											255,000
Purchase price, including closing costs											$ 38,794,000
Acquisition costs incurred											$ 283,000
Weighted average amortization period											2 years 7 months 6 days
Mortgage debt assumed											$ 0
Acquired real estate lease obligations											0
MOBs | Acquisitions | 2 States | Land
Real Estate Properties
Net Book Value of Collateral											6,738,000
MOBs | Acquisitions | 2 States | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral											$ 25,040,000
MOBs | Acquisitions | California
Real Estate Properties
Acquired real estate leases										$ 5,436,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property										1
Number of buildings acquired | building										1
Area of real estate properties (in square feet) | ft²										63,000
Purchase price, including closing costs										$ 26,823,000
Acquisition costs incurred										$ 323,000
Weighted average amortization period										8 years 8 months 12 days
Mortgage debt assumed										$ 0
Acquired real estate lease obligations										0
MOBs | Acquisitions | California | Land
Real Estate Properties
Net Book Value of Collateral										7,957,000
MOBs | Acquisitions | California | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral										$ 13,430,000
MOBs | Acquisitions | Minnesota
Real Estate Properties
Acquired real estate leases																							$ 5,053,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property																							1
Number of buildings acquired | building																							3
Area of real estate properties (in square feet) | ft²																							128,000
Weighted average amortization period																							6 years 4 months 24 days
Below market, acquired lease amortization period																							7 years 3 months 19 days
Mortgage debt assumed																							$ 0
Purchase price excluding closing costs																							22,700,000
Acquired real estate lease obligations																							1,091,000
MOBs | Acquisitions | Minnesota | Land
Real Estate Properties
Net Book Value of Collateral																							4,028,000
MOBs | Acquisitions | Minnesota | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral																							$ 14,710,000
MOBs | Acquisitions | Florida
Real Estate Properties
Acquired real estate leases																				$ 0
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property																				1
Number of buildings acquired | building																				1
Area of real estate properties (in square feet) | ft²																				166,000
Purchase price, including closing costs																				$ 45,232,000
Acquisition costs incurred																				232,000
Mortgage debt assumed																				0
Acquired real estate lease obligations																				0
MOBs | Acquisitions | Florida | Land
Real Estate Properties
Net Book Value of Collateral																				2,792,000
MOBs | Acquisitions | Florida | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral																				$ 42,440,000
MOBs | Acquisitions | Ohio
Real Estate Properties
Acquired real estate leases																$ 4,592,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property																1
Number of buildings acquired | building																1
Area of real estate properties (in square feet) | ft²																96,000
Weighted average amortization period																14 years 1 month 6 days
Mortgage debt assumed																$ 0
Purchase price excluding closing costs																18,500,000
Acquired real estate lease obligations																0
MOBs | Acquisitions | Ohio | Land
Real Estate Properties
Net Book Value of Collateral																1,025,000
MOBs | Acquisitions | Ohio | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral																$ 12,883,000
Senior Living Communities | Virginia
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Gain on sale of properties									45,901,000
Sale price of property sold and agreed to be sold									$ 55,000,000
Number of real estate properties sold | community									1
Senior Living Communities | Georgia
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of communities | community															5
Lease termination fee															$ 115,000
Senior Living Communities | 4 States
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property																			7
Number of private pay independent living units | living_unit																			545
Purchase price excluding closing costs																			$ 112,350,000
Number of states in which properties are located | state																			4
Operating leases annual rent																			$ 8,426,000
Senior Living Communities | Illinois
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | community															2
Number of private pay independent living units | living_unit															126
Purchase price excluding closing costs															$ 18,600,000
Senior Living Communities | California Colorado And Oregon
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | community																									3
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Impairment of assets																									$ 19,549,000
Senior Living Communities | Romeoville, IL
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Gain on sale of properties									$ 154,000
Senior Living Communities | Acquisitions
Real Estate Properties
Acquired real estate leases			$ 11,489,000												$ 3,723,000										$ 11,489,000		$ 3,723,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property																									4		10
Mortgage debt assumed																									$ 33,336,000		$ 0
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Number of units | living_unit			366												709										366		709
Senior Living Communities | Acquisitions | Land
Real Estate Properties
Net Book Value of Collateral			$ 3,562,000												$ 13,226,000										$ 3,562,000		$ 13,226,000
Senior Living Communities | Acquisitions | Buildings and Improvements
Real Estate Properties
Net Book Value of Collateral			49,917,000												$ 114,512,000										49,917,000		$ 114,512,000
Triple Net Leased Senior Living Communities
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Increase in annual lease rent payable																									1,816,000	4,870,000
Number of communities | community																											2
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Impairment of assets																											$ 4,391,000
Real estate improvements by lessee purchased																									23,376,000	51,952,000
Skilled Nursing Facility | North Carolina
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Gain on sale of properties																					$ 2,365,000
Above Market Leases
Real Estate Properties
Acquired real estate leases			35,056,000						40,540,000																35,056,000	40,540,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Accumulated amortization			27,375,000						29,900,000																27,375,000	29,900,000
Leases, Acquired-in-Place
Real Estate Properties
Acquired real estate leases			656,163,000						750,527,000																656,163,000	750,527,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Accumulated amortization			244,600,000						$ 288,902,000																244,600,000	288,902,000
Five Star
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Increase in annual lease rent payable																									1,433,000	3,193,000	1,719,000
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Impairment of assets																								$ 5,082,000
Number of units | living_unit																												238
Real estate improvements by lessee purchased																									17,956,000	39,800,000	$ 21,438,000
Five Star | Senior Living Communities
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of pre-existing management agreements terminated | pooling_agreement	3																		3
Number of pre-existing management agreements	4																		4
Number of separate management agreements entered for communities acquired | pooling_agreement																			10
Five Star | Senior Living Communities | Florida
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Purchase price excluding closing costs																	$ 130,000
Increase in annual lease rent payable																	10,000
Five Star | Senior Living Communities | Illinois
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | community															2
Increase in annual lease rent payable															$ 1,395,000
Five Star | Senior Living Communities | Acquisitions
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property										6
Five Star | Senior Living Communities | Acquisitions | Alabama and Indiana
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | property									2
Purchase price, including closing costs									$ 39,457,000
Acquisition costs incurred									$ 307,000
Number of private pay independent living units | living_unit									229
Five Star | Senior Living Communities | Acquisitions | Tennessee
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | community				2				1
Acquisition costs incurred				$ 560,000				$ 201,000
Mortgage debt assumed				$ 16,588,000
Number of private pay independent living units | living_unit				151				88
Purchase price excluding closing costs				$ 23,860,000				$ 19,868,000
Five Star | Senior Living Communities | Acquisitions | Arizona
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | community							1
Acquisition costs incurred							$ 372,000
Mortgage debt assumed							$ 16,748,000
Number of private pay independent living units | living_unit							127
Purchase price excluding closing costs							$ 22,622,000
Five Star | Senior Living Communities | Acquisitions | Delaware
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Purchase price excluding closing costs												$ 750,000
Increase in annual lease rent payable												$ 33,000
Five Star | Land Parcel | Georgia
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Purchase price excluding closing costs															1,600,000
TRS
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Impairment of assets																										0
TRS | Managed Senior Living Communities | Georgia
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Number of properties acquired or agreed to be acquired | community																				1
Number of private pay independent living units | living_unit																				38
Purchase price excluding closing costs																				$ 8,400,000
Discontinued operations, disposed of by sale | California
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Gain on sale of properties				2,150,000
Discontinued operations, disposed of by sale | MOBs
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Sale price of property sold and agreed to be sold																		$ 20,150,000
Number of properties sold | property																		4
Number of buildings sold | building																		4
Discontinued operations, disposed of by sale | MOBs | Florida
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Sale price of property sold and agreed to be sold															2,100,000
Discontinued operations, disposed of by sale | MOBs | Massachusetts
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Sale price of property sold and agreed to be sold			$ 2,050,000
Number of real estate properties sold | community			2
Discontinued operations, disposed of by sale | MOBs | Pennsylvania
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Sale price of property sold and agreed to be sold															$ 2,800,000
Number of properties sold | property															1
Discontinued operations, disposed of by sale | Skilled Nursing Facility
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Gain on sale of properties																			$ 4,061,000
Sale price of property sold and agreed to be sold																	248,000		$ 9,100,000
Discontinued operations, disposed of by sale | Land Parcel
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Sale price of property sold and agreed to be sold																						$ 700,000
Discontinued operations, disposed of by sale | Five Star
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Increase in annual lease rent payable																	$ 25,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | MOBs
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Number of land parcels sold | parcel																											1
Number of communities sold | community																											2
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Sunrise Senior Living LLC
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Gain on sale of properties				1,906,000
Sale price of property sold and agreed to be sold				$ 21,865,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Sunrise Senior Living LLC | Senior Living Communities
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Gain on sale of properties					$ 78,856,000	$ 181,154,000
Number of communities sold | community				1	1	2
Sale price of property sold and agreed to be sold					$ 96,000,000	$ 217,000,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Sunrise Senior Living LLC | Skilled Nursing Facility
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Number of real estate properties held for sale | nursing_facility				1
Rental income				$ 650,000
Discontinued Operations, Held-for-sale
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Number of real estate properties held for sale | property															0												0
Real estate held for sale			$ 1,928,000						$ 53,338,000																$ 1,928,000	$ 53,338,000
Discontinued Operations, Held-for-sale | Triple Net Leased Senior Living Communities
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Number of real estate properties held for sale | property			2						4																2	4
Number of units | living_unit			1,295																						1,295
Area of real estate properties leased (in square feet) | ft²			32,604
Weighted Average
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Below market lease, remaining amortization period																									9 years 9 months 20 days
Weighted Average | Above Market Leases
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Finite-lived intangibles, remaining amortization period																									4 years 4 months 8 days
Weighted Average | Leases, Acquired-in-Place
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Finite-lived intangibles, remaining amortization period																									8 years 9 months 18 days
Subsequent Event | Disposal Group, Disposed of by Sale, Not Discontinued Operations | MOBs | Florida
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Number of communities sold | community		1
Sale price of property sold and agreed to be sold		$ 2,900,000
Subsequent Event | Disposal Group, Disposed of by Sale, Not Discontinued Operations | MOBs | Colorado
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Number of communities sold | community		1
Sale price of property sold and agreed to be sold		$ 2,625,000

X

- Definition

Acquired Above Market Lease Amortization Period

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

X

- Definition

Amortization period for leases with a finite life acquired as part of a real property acquisition at below market lease rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	snh_
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- Definition

Acquisition Costs Incurred

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No definition available.

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- Definition

Remaining amortization period of leases at below market lease rate with a finite life.

+ References

No definition available.

+ Details

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- Definition

This element represents the aggregate purchase price of real estate properties acquired by the entity during the period. This amount includes cash paid plus debt assumed, if any, and other settlement adjustments but excludes closing costs.

+ References

No definition available.

+ Details

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Cash Paid plus Assumed Debt, including closing costs plus other settlement adjustments

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No definition available.

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- 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

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- Definition

Amount of committed but unspent tenant related obligations based on executed lease.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Represents the amount of expenditure committed by entity relating to leases.

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No definition available.

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Namespace Prefix:	snh_
Data Type:	xbrli:monetaryItemType
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- Definition

Represents the number of private pay independent living units within communities acquired.

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No definition available.

+ Details

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- Definition

Represents the number of buildings acquired or agreed to be acquired by the entity.

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No definition available.

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- Definition

This element represents the number of buildings sold by the entity.

+ References

No definition available.

+ Details

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Balance Type:	na
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Represents the number of communities.

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No definition available.

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Represents the number of communities sold.

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No definition available.

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Number Of Land Parcels Sold

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No definition available.

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- Definition

Represents the number of pre-existing management agreements.

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Number of Pre-Existing Management Agreements Terminated

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Represents the number of properties acquired or agreed to be acquired by the entity.

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- Definition

This element represents the number of properties sold or agreed to be sold by the entity.

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The number of real estate properties owned by the entity, which are classified as held for sale as of the balance sheet date.

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Represents the number of separate management agreements entered for communities acquired, upon termination of a pre-existing combined management agreement.

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Number of Real Estate Properties Sold

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- Definition

This element represents the aggregate sales price excluding closing costs, of real estate properties sold by the entity.

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Represents the amount of improvements to real estate properties made by lessees and purchased by the entity.

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No definition available.

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Represents the intangible lease assets recorded as part of the real estate acquisition.

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No definition available.

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Represents the intangible lease liabilities recorded as part of the real estate acquisition.

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Represents the area of the real estate property subject to an operating lease.

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Area of a real estate property.

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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.

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Amount of accumulated amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life.

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Amount of rental income attributable to disposal group, including, but not limited to, discontinued operation.

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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.

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No definition available.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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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.

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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.

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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.

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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.

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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.

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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.

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No definition available.

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Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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Gain (loss) related to the termination of a contract between the parties. The termination may be due to many causes including early termination of a lease by a lessee, a breach of contract by one party, or a failure to perform.

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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.

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Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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No definition available.

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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.

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- Definition

The number of states the entity operates in as of the balance sheet date.

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No definition available.

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- Definition

The number of units in a real estate property owned as of the balance sheet date.

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No definition available.

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- References

No definition available.

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Future rental payments receivable within one year of the balance sheet date under an operating lease.

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Future rental payments receivable within the fifth year from the balance sheet date under an operating lease.

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Future rental payments receivable within the fourth year from the balance sheet date under an operating lease.

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Future rental payments receivable within the third year from the balance sheet date under an operating lease.

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Future rental payments receivable within the second year from the balance sheet date under an operating lease.

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Future minimum lease payments receivable under operating leases for periods greater than five years following the balance sheet date.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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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.

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The cumulative amount of depreciation for real estate property held for investment purposes.

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