XML 89 R69.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Real Estate and Accumulated Depreciation (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | $ 805,178 bfs_RealEstateInvestmentPropertyCostInitialBasis |  |  |  |
Cost Capitalized Subsequent to Acquisition | 730,226 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition |  |  |  |
Basis at Close of Period, Land | 423,052 us-gaap_LandAndLandImprovements |  |  |  |
Basis at Close of Period, Building and Improvements | 1,135,286 us-gaap_BuildingsAndImprovementsGross |  |  |  |
Basis at Close of Period, Leasehold Interests | 1,821 us-gaap_RealEstateInvestmentsOther |  |  |  |
Total | 1,560,159 us-gaap_RealEstateInvestmentPropertyAtCost |  | 1,459,439 us-gaap_RealEstateInvestmentPropertyAtCost | 1,466,068 us-gaap_RealEstateInvestmentPropertyAtCost | 1,417,845 us-gaap_RealEstateInvestmentPropertyAtCost
Accumulated Depreciation | 396,617 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation |  | 364,663 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation | 353,305 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation | 326,397 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation
Book Value | 1,163,542 us-gaap_RealEstateInvestmentPropertyNet |  | 1,094,776 us-gaap_RealEstateInvestmentPropertyNet |  |
Related Debt | 808,997 us-gaap_SecuredDebt |  | 820,068 us-gaap_SecuredDebt |  |
Development Land, Related Debt | 5,391 us-gaap_ConstructionLoan |  | 0 us-gaap_ConstructionLoan |  |
Total, Related Debt | 814,388 bfs_SecuredDebtIncludingConstructionLoan |  |  |  |
Shopping Centers |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 750,377 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 394,340 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember |  |  |  |
Basis at Close of Period, Land | 384,569 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember |  |  |  |
Basis at Close of Period, Building and Improvements | 758,327 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 1,821 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember |  |  |  |
Total | 1,144,717 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember |  |  |  |
Accumulated Depreciation | 270,400 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember |  |  |  |
Book Value | 874,317 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember |  |  |  |
Related Debt | 631,228 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember |  |  |  |
Shopping Centers | Ashburn Village, Ashburn, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 11,431 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyOneMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 19,492 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyOneMember |  |  |  |
Basis at Close of Period, Land | 6,764 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyOneMember |  |  |  |
Basis at Close of Period, Building and Improvements | 24,159 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyOneMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyOneMember |  |  |  |
Total | 30,923 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyOneMember |  |  |  |
Accumulated Depreciation | 10,868 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyOneMember |  |  |  |
Book Value | 20,055 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyOneMember |  |  |  |
Related Debt | 30,253 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyOneMember |  |  |  |
Date Acquired | 1994-03 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Ashburn Village, Ashburn, VA | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1994 |  |  |  |
Shopping Centers | Ashburn Village, Ashburn, VA | Construction One | Minimum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2000 |  |  |  |
Shopping Centers | Ashburn Village, Ashburn, VA | Construction One | Maximum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2006 |  |  |  |
Shopping Centers | Ashland Square Phase I, Dumfries, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 1,178 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwoMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 7,503 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwoMember |  |  |  |
Basis at Close of Period, Land | 1,178 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwoMember |  |  |  |
Basis at Close of Period, Building and Improvements | 7,503 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwoMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwoMember |  |  |  |
Total | 8,681 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwoMember |  |  |  |
Accumulated Depreciation | 776 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwoMember |  |  |  |
Book Value | 7,905 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwoMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwoMember |  |  |  |
Date Acquired | 2004-12 |  |  |  |
Shopping Centers | Ashland Square Phase I, Dumfries, VA | Minimum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 20 years |  |  |  |
Shopping Centers | Ashland Square Phase I, Dumfries, VA | Maximum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | Ashland Square Phase I, Dumfries, VA | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2007 |  |  |  |
Shopping Centers | Ashland Square Phase I, Dumfries, VA | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2013 |  |  |  |
Shopping Centers | Beacon Center, Alexandria, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 1,493 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThreeMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 18,232 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThreeMember |  |  |  |
Basis at Close of Period, Land | 0 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThreeMember |  |  |  |
Basis at Close of Period, Building and Improvements | 18,631 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThreeMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 1,094 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThreeMember |  |  |  |
Total | 19,725 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThreeMember |  |  |  |
Accumulated Depreciation | 12,707 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThreeMember |  |  |  |
Book Value | 7,018 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThreeMember |  |  |  |
Related Debt | 33,140 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThreeMember |  |  |  |
Date Acquired | 1972-01 |  |  |  |
Shopping Centers | Beacon Center, Alexandria, VA | Minimum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Beacon Center, Alexandria, VA | Maximum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | Beacon Center, Alexandria, VA | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1960 |  |  |  |
Shopping Centers | Beacon Center, Alexandria, VA | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1974 |  |  |  |
Shopping Centers | BJ’s Wholesale Club, Alexandria, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 22,623 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 0 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourMember |  |  |  |
Basis at Close of Period, Land | 22,623 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourMember |  |  |  |
Basis at Close of Period, Building and Improvements | 0 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourMember |  |  |  |
Total | 22,623 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourMember |  |  |  |
Book Value | 22,623 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourMember |  |  |  |
Related Debt | 11,587 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourMember |  |  |  |
Date Acquired | 2008-03 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 0 years |  |  |  |
Shopping Centers | Boca Valley Plaza, Boca Raton, FL |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 16,720 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiveMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 1,297 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiveMember |  |  |  |
Basis at Close of Period, Land | 5,735 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiveMember |  |  |  |
Basis at Close of Period, Building and Improvements | 12,282 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiveMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiveMember |  |  |  |
Total | 18,017 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiveMember |  |  |  |
Accumulated Depreciation | 3,478 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiveMember |  |  |  |
Book Value | 14,539 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiveMember |  |  |  |
Related Debt | 10,881 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiveMember |  |  |  |
Date Acquired | 2004-02 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Boulevard, Fairfax, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 4,883 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 4,487 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixMember |  |  |  |
Basis at Close of Period, Land | 3,687 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixMember |  |  |  |
Basis at Close of Period, Building and Improvements | 5,683 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixMember |  |  |  |
Total | 9,370 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixMember |  |  |  |
Accumulated Depreciation | 2,194 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixMember |  |  |  |
Book Value | 7,176 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixMember |  |  |  |
Related Debt | 9,239 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixMember |  |  |  |
Date Acquired | 1994-04 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Boulevard, Fairfax, VA | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1969 |  |  |  |
Shopping Centers | Boulevard, Fairfax, VA | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1999 |  |  |  |
Shopping Centers | Boulevard, Fairfax, VA | Construction Three |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2009 |  |  |  |
Shopping Centers | Briggs Chaney MarketPlace, Silver Spring, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 27,037 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySevenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 2,957 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySevenMember |  |  |  |
Basis at Close of Period, Land | 9,789 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySevenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 20,205 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySevenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySevenMember |  |  |  |
Total | 29,994 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySevenMember |  |  |  |
Accumulated Depreciation | 6,076 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySevenMember |  |  |  |
Book Value | 23,918 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySevenMember |  |  |  |
Related Debt | 15,761 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySevenMember |  |  |  |
Date Acquired | 2004-04 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Broadlands Village, Ashburn, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 5,316 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEightMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 25,285 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEightMember |  |  |  |
Basis at Close of Period, Land | 5,300 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEightMember |  |  |  |
Basis at Close of Period, Building and Improvements | 25,301 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEightMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEightMember |  |  |  |
Total | 30,601 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEightMember |  |  |  |
Accumulated Depreciation | 8,354 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEightMember |  |  |  |
Book Value | 22,247 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEightMember |  |  |  |
Related Debt | 18,826 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEightMember |  |  |  |
Date Acquired | 2002-03 |  |  |  |
Shopping Centers | Broadlands Village, Ashburn, VA | Minimum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Broadlands Village, Ashburn, VA | Maximum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | Broadlands Village, Ashburn, VA | Construction One | Minimum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2002 |  |  |  |
Shopping Centers | Broadlands Village, Ashburn, VA | Construction One | Maximum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2003 |  |  |  |
Shopping Centers | Broadlands Village, Ashburn, VA | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2004 |  |  |  |
Shopping Centers | Broadlands Village, Ashburn, VA | Construction Three |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2006 |  |  |  |
Shopping Centers | Countryside Marketplace, Sterling, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 28,912 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 3,039 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineMember |  |  |  |
Basis at Close of Period, Land | 7,666 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineMember |  |  |  |
Basis at Close of Period, Building and Improvements | 24,285 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineMember |  |  |  |
Total | 31,951 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineMember |  |  |  |
Accumulated Depreciation | 6,538 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineMember |  |  |  |
Book Value | 25,413 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineMember |  |  |  |
Related Debt | 15,819 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineMember |  |  |  |
Date Acquired | 2004-02 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Cranberry Square, Westminster, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 31,578 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 464 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTenMember |  |  |  |
Basis at Close of Period, Land | 6,700 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 25,342 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTenMember |  |  |  |
Total | 32,042 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTenMember |  |  |  |
Accumulated Depreciation | 2,061 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTenMember |  |  |  |
Book Value | 29,981 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTenMember |  |  |  |
Related Debt | 18,645 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTenMember |  |  |  |
Date Acquired | 2011-09 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Cruse MarketPlace, Cumming, GA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 12,226 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyElevenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 198 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyElevenMember |  |  |  |
Basis at Close of Period, Land | 3,920 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyElevenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 8,504 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyElevenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyElevenMember |  |  |  |
Total | 12,424 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyElevenMember |  |  |  |
Accumulated Depreciation | 2,350 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyElevenMember |  |  |  |
Book Value | 10,074 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyElevenMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyElevenMember |  |  |  |
Date Acquired | 2004-03 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Flagship Center, Rockville, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 160 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwelveMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 9 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwelveMember |  |  |  |
Basis at Close of Period, Land | 169 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwelveMember |  |  |  |
Basis at Close of Period, Building and Improvements | 0 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwelveMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwelveMember |  |  |  |
Total | 169 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwelveMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwelveMember |  |  |  |
Book Value | 169 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwelveMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwelveMember |  |  |  |
Date of Construction | 1972 |  |  |  |
Date Acquired | 1972-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 0 years |  |  |  |
Shopping Centers | French Market, Oklahoma City, OK |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 5,781 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirteenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 13,782 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirteenMember |  |  |  |
Basis at Close of Period, Land | 1,118 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirteenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 18,445 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirteenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirteenMember |  |  |  |
Total | 19,563 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirteenMember |  |  |  |
Accumulated Depreciation | 9,444 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirteenMember |  |  |  |
Book Value | 10,119 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirteenMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirteenMember |  |  |  |
Date Acquired | 1974-03 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | French Market, Oklahoma City, OK | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1972 |  |  |  |
Shopping Centers | French Market, Oklahoma City, OK | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1998 |  |  |  |
Shopping Centers | Germantown, Germantown, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 3,576 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourteenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 743 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourteenMember |  |  |  |
Basis at Close of Period, Land | 2,034 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourteenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 2,285 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourteenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourteenMember |  |  |  |
Total | 4,319 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourteenMember |  |  |  |
Accumulated Depreciation | 1,385 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourteenMember |  |  |  |
Book Value | 2,934 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourteenMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFourteenMember |  |  |  |
Date of Construction | 1990 |  |  |  |
Date Acquired | 1993-08 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | 750/730 N. Glebe Road, Arlington, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 42,313 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_A750730NorthGlebeArlingtonVAMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 13 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_A750730NorthGlebeArlingtonVAMember |  |  |  |
Basis at Close of Period, Land | 40,907 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_A750730NorthGlebeArlingtonVAMember |  |  |  |
Basis at Close of Period, Building and Improvements | 1,419 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_A750730NorthGlebeArlingtonVAMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_A750730NorthGlebeArlingtonVAMember |  |  |  |
Total | 42,326 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_A750730NorthGlebeArlingtonVAMember |  |  |  |
Accumulated Depreciation | 160 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_A750730NorthGlebeArlingtonVAMember |  |  |  |
Book Value | 42,166 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_A750730NorthGlebeArlingtonVAMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_A750730NorthGlebeArlingtonVAMember |  |  |  |
Shopping Centers | 750/730 N. Glebe Road, Arlington, VA | Acquisition Date One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2014-08 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 3 years |  |  |  |
Shopping Centers | 750/730 N. Glebe Road, Arlington, VA | Acquisition Date Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2014-12 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 2 years |  |  |  |
Shopping Centers | The Glen, Woodbridge, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 12,918 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixteenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 7,536 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixteenMember |  |  |  |
Basis at Close of Period, Land | 5,299 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixteenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 15,155 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixteenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixteenMember |  |  |  |
Total | 20,454 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixteenMember |  |  |  |
Accumulated Depreciation | 7,327 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixteenMember |  |  |  |
Book Value | 13,127 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixteenMember |  |  |  |
Related Debt | 9,045 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySixteenMember |  |  |  |
Date Acquired | 1994-06 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | The Glen, Woodbridge, VA | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1993 |  |  |  |
Shopping Centers | The Glen, Woodbridge, VA | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2005 |  |  |  |
Shopping Centers | Great Eastern, District Heights, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 4,993 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySeventeenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 10,669 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySeventeenMember |  |  |  |
Basis at Close of Period, Land | 3,785 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySeventeenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 11,877 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySeventeenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySeventeenMember |  |  |  |
Total | 15,662 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySeventeenMember |  |  |  |
Accumulated Depreciation | 7,726 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySeventeenMember |  |  |  |
Book Value | 7,936 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySeventeenMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertySeventeenMember |  |  |  |
Date Acquired | 1972-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Great Eastern, District Heights, MD | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1958 |  |  |  |
Shopping Centers | Great Eastern, District Heights, MD | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1960 |  |  |  |
Shopping Centers | Great Falls Center, Great Falls, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 41,750 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEighteenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 2,350 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEighteenMember |  |  |  |
Basis at Close of Period, Land | 14,766 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEighteenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 29,334 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEighteenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEighteenMember |  |  |  |
Total | 44,100 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEighteenMember |  |  |  |
Accumulated Depreciation | 4,988 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEighteenMember |  |  |  |
Book Value | 39,112 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEighteenMember |  |  |  |
Related Debt | 14,909 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyEighteenMember |  |  |  |
Date Acquired | 2008-03 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Hampshire Langley, Takoma, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 3,159 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineteenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 3,338 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineteenMember |  |  |  |
Basis at Close of Period, Land | 1,856 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineteenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 4,641 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineteenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineteenMember |  |  |  |
Total | 6,497 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineteenMember |  |  |  |
Accumulated Depreciation | 3,351 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineteenMember |  |  |  |
Book Value | 3,146 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineteenMember |  |  |  |
Related Debt | 17,281 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyNineteenMember |  |  |  |
Date of Construction | 1960 |  |  |  |
Date Acquired | 1972-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Hunt Club Corners, Apopka, FL |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 12,584 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 3,115 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyMember |  |  |  |
Basis at Close of Period, Land | 4,822 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyMember |  |  |  |
Basis at Close of Period, Building and Improvements | 10,877 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyMember |  |  |  |
Total | 15,699 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyMember |  |  |  |
Accumulated Depreciation | 2,555 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyMember |  |  |  |
Book Value | 13,144 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyMember |  |  |  |
Related Debt | 6,100 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyMember |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Hunt Club Corners, Apopka, FL | Acquisition Date One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2006-06 |  |  |  |
Shopping Centers | Hunt Club Corners, Apopka, FL | Acquisition Date Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2012-12 |  |  |  |
Shopping Centers | Jamestown Place, Altamonte Springs, FL |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 14,055 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyOneMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 960 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyOneMember |  |  |  |
Basis at Close of Period, Land | 4,455 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyOneMember |  |  |  |
Basis at Close of Period, Building and Improvements | 10,560 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyOneMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyOneMember |  |  |  |
Total | 15,015 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyOneMember |  |  |  |
Accumulated Depreciation | 2,532 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyOneMember |  |  |  |
Book Value | 12,483 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyOneMember |  |  |  |
Related Debt | 8,346 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyOneMember |  |  |  |
Date Acquired | 2005-11 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Kentlands Square I, Gaithersburg, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 14,379 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyTwoMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 177 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyTwoMember |  |  |  |
Basis at Close of Period, Land | 5,006 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyTwoMember |  |  |  |
Basis at Close of Period, Building and Improvements | 9,550 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyTwoMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyTwoMember |  |  |  |
Total | 14,556 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyTwoMember |  |  |  |
Accumulated Depreciation | 2,958 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyTwoMember |  |  |  |
Book Value | 11,598 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyTwoMember |  |  |  |
Related Debt | 7,527 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyTwoMember |  |  |  |
Date of Construction | 2002 |  |  |  |
Date Acquired | 2002-09 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Kentlands Square II, Gaithersburg, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 76,723 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyThreeMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 954 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyThreeMember |  |  |  |
Basis at Close of Period, Land | 22,800 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyThreeMember |  |  |  |
Basis at Close of Period, Building and Improvements | 54,877 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyThreeMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyThreeMember |  |  |  |
Total | 77,677 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyThreeMember |  |  |  |
Accumulated Depreciation | 4,387 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyThreeMember |  |  |  |
Book Value | 73,290 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyThreeMember |  |  |  |
Related Debt | 39,932 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyThreeMember |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Kentlands Square II, Gaithersburg, MD | Acquisition Date One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2011-09 |  |  |  |
Shopping Centers | Kentlands Square II, Gaithersburg, MD | Acquisition Date Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2013-09 |  |  |  |
Shopping Centers | Kentlands Place, Gaithersburg, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 1,425 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFourMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 7,163 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFourMember |  |  |  |
Basis at Close of Period, Land | 1,425 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFourMember |  |  |  |
Basis at Close of Period, Building and Improvements | 7,163 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFourMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFourMember |  |  |  |
Total | 8,588 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFourMember |  |  |  |
Accumulated Depreciation | 2,863 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFourMember |  |  |  |
Book Value | 5,725 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFourMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFourMember |  |  |  |
Date of Construction | 2005 |  |  |  |
Date Acquired | 2004-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | Lansdowne Town Center, Leesburg, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 6,545 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFiveMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 36,313 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFiveMember |  |  |  |
Basis at Close of Period, Land | 6,546 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFiveMember |  |  |  |
Basis at Close of Period, Building and Improvements | 36,312 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFiveMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFiveMember |  |  |  |
Total | 42,858 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFiveMember |  |  |  |
Accumulated Depreciation | 10,174 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFiveMember |  |  |  |
Book Value | 32,684 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFiveMember |  |  |  |
Related Debt | 35,222 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyFiveMember |  |  |  |
Date of Construction | 2006 |  |  |  |
Date Acquired | 2002-11 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | Leesburg Pike Plaza, Baileys Crossroads, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 2,418 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySixMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 6,173 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySixMember |  |  |  |
Basis at Close of Period, Land | 1,132 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySixMember |  |  |  |
Basis at Close of Period, Building and Improvements | 7,459 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySixMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySixMember |  |  |  |
Total | 8,591 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySixMember |  |  |  |
Accumulated Depreciation | 5,582 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySixMember |  |  |  |
Book Value | 3,009 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySixMember |  |  |  |
Related Debt | 16,750 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySixMember |  |  |  |
Date of Construction | 1965 |  |  |  |
Date Acquired | 1966-02 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Lumberton Plaza, Lumberton, NJ |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 4,400 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySevenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 11,160 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySevenMember |  |  |  |
Basis at Close of Period, Land | 950 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySevenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 14,610 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySevenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySevenMember |  |  |  |
Total | 15,560 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySevenMember |  |  |  |
Accumulated Depreciation | 11,676 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySevenMember |  |  |  |
Book Value | 3,884 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySevenMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentySevenMember |  |  |  |
Date of Construction | 1975 |  |  |  |
Date Acquired | 1975-12 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Metro Pike Center, Rockville, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 33,123 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyEightMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 2,069 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyEightMember |  |  |  |
Basis at Close of Period, Land | 26,064 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyEightMember |  |  |  |
Basis at Close of Period, Building and Improvements | 9,128 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyEightMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyEightMember |  |  |  |
Total | 35,192 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyEightMember |  |  |  |
Accumulated Depreciation | 771 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyEightMember |  |  |  |
Book Value | 34,421 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyEightMember |  |  |  |
Related Debt | 15,106 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyEightMember |  |  |  |
Date Acquired | 2010-12 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Shops at Monocacy, Frederick, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 9,541 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyNineMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 14,002 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyNineMember |  |  |  |
Basis at Close of Period, Land | 9,260 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyNineMember |  |  |  |
Basis at Close of Period, Building and Improvements | 14,283 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyNineMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyNineMember |  |  |  |
Total | 23,543 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyNineMember |  |  |  |
Accumulated Depreciation | 4,320 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyNineMember |  |  |  |
Book Value | 19,223 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyNineMember |  |  |  |
Related Debt | 14,014 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyTwentyNineMember |  |  |  |
Date Acquired | 2003-11 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | Shops at Monocacy, Frederick, MD | Construction One | Minimum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2003 |  |  |  |
Shopping Centers | Shops at Monocacy, Frederick, MD | Construction One | Maximum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2004 |  |  |  |
Shopping Centers | Northrock, Warrenton, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 12,686 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 14,981 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyMember |  |  |  |
Basis at Close of Period, Land | 12,686 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyMember |  |  |  |
Basis at Close of Period, Building and Improvements | 14,981 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyMember |  |  |  |
Total | 27,667 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyMember |  |  |  |
Accumulated Depreciation | 2,283 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyMember |  |  |  |
Book Value | 25,384 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyMember |  |  |  |
Related Debt | 14,525 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyMember |  |  |  |
Date of Construction | 2009 |  |  |  |
Date Acquired | 2008-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | Olde Forte Village, Ft. Washington, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 15,933 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyOneMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 6,499 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyOneMember |  |  |  |
Basis at Close of Period, Land | 5,409 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyOneMember |  |  |  |
Basis at Close of Period, Building and Improvements | 17,023 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyOneMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyOneMember |  |  |  |
Total | 22,432 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyOneMember |  |  |  |
Accumulated Depreciation | 5,583 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyOneMember |  |  |  |
Book Value | 16,849 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyOneMember |  |  |  |
Related Debt | 11,454 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyOneMember |  |  |  |
Date Acquired | 2007-03 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Olde Forte Village, Ft. Washington, MD | Construction One | Minimum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2003 |  |  |  |
Shopping Centers | Olde Forte Village, Ft. Washington, MD | Construction One | Maximum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2004 |  |  |  |
Shopping Centers | Olney, Olney, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 1,884 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyTwoMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 1,672 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyTwoMember |  |  |  |
Basis at Close of Period, Land | 0 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyTwoMember |  |  |  |
Basis at Close of Period, Building and Improvements | 3,556 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyTwoMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyTwoMember |  |  |  |
Total | 3,556 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyTwoMember |  |  |  |
Accumulated Depreciation | 3,180 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyTwoMember |  |  |  |
Book Value | 376 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyTwoMember |  |  |  |
Related Debt | 11,119 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyTwoMember |  |  |  |
Date of Construction | 1972 |  |  |  |
Date Acquired | 1975-11 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Orchard Park, Dunwoody, GA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 19,377 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyThreeMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 781 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyThreeMember |  |  |  |
Basis at Close of Period, Land | 7,751 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyThreeMember |  |  |  |
Basis at Close of Period, Building and Improvements | 12,407 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyThreeMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyThreeMember |  |  |  |
Total | 20,158 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyThreeMember |  |  |  |
Accumulated Depreciation | 2,343 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyThreeMember |  |  |  |
Book Value | 17,815 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyThreeMember |  |  |  |
Related Debt | 10,718 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyThreeMember |  |  |  |
Date Acquired | 2007-07 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Palm Springs Center, Altamonte Springs, FL |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 18,365 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFourMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 659 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFourMember |  |  |  |
Basis at Close of Period, Land | 5,739 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFourMember |  |  |  |
Basis at Close of Period, Building and Improvements | 13,285 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFourMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFourMember |  |  |  |
Total | 19,024 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFourMember |  |  |  |
Accumulated Depreciation | 3,247 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFourMember |  |  |  |
Book Value | 15,777 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFourMember |  |  |  |
Related Debt | 9,535 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFourMember |  |  |  |
Date Acquired | 2005-03 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Ravenwood, Baltimore, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 1,245 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFiveMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 4,097 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFiveMember |  |  |  |
Basis at Close of Period, Land | 703 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFiveMember |  |  |  |
Basis at Close of Period, Building and Improvements | 4,639 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFiveMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFiveMember |  |  |  |
Total | 5,342 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFiveMember |  |  |  |
Accumulated Depreciation | 2,602 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFiveMember |  |  |  |
Book Value | 2,740 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFiveMember |  |  |  |
Related Debt | 15,735 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyFiveMember |  |  |  |
Date Acquired | 1972-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Ravenwood, Baltimore, MD | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1959 |  |  |  |
Shopping Centers | Ravenwood, Baltimore, MD | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2006 |  |  |  |
Shopping Centers | 11503 Rockville Pike/5541 Nicholson Lane, Rockville, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 14,861 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySixMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 11,700 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySixMember |  |  |  |
Basis at Close of Period, Land | 22,113 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySixMember |  |  |  |
Basis at Close of Period, Building and Improvements | 4,448 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySixMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySixMember |  |  |  |
Total | 26,561 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySixMember |  |  |  |
Accumulated Depreciation | 473 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySixMember |  |  |  |
Book Value | 26,088 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySixMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySixMember |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | 11503 Rockville Pike/5541 Nicholson Lane, Rockville, MD | Acquisition Date One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2010-10 |  |  |  |
Shopping Centers | 11503 Rockville Pike/5541 Nicholson Lane, Rockville, MD | Acquisition Date Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2012-12 |  |  |  |
Shopping Centers | 1500/1580/1582/1584 Rockville Pike, Rockville, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 51,156 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySevenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 568 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySevenMember |  |  |  |
Basis at Close of Period, Land | 43,863 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySevenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 7,861 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySevenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySevenMember |  |  |  |
Total | 51,724 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySevenMember |  |  |  |
Accumulated Depreciation | 1,962 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySevenMember |  |  |  |
Book Value | 49,762 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySevenMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtySevenMember |  |  |  |
Date Acquired | 2012-12 |  |  |  |
Shopping Centers | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2014-01 |  |  |  |
Shopping Centers | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date Three |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2014-04 |  |  |  |
Shopping Centers | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date Four |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2014-12 |  |  |  |
Shopping Centers | Seabreeze Plaza, Palm Harbor, FL |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 24,526 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyEightMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 1,391 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyEightMember |  |  |  |
Basis at Close of Period, Land | 8,665 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyEightMember |  |  |  |
Basis at Close of Period, Building and Improvements | 17,252 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyEightMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyEightMember |  |  |  |
Total | 25,917 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyEightMember |  |  |  |
Accumulated Depreciation | 4,056 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyEightMember |  |  |  |
Book Value | 21,861 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyEightMember |  |  |  |
Related Debt | 17,462 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyEightMember |  |  |  |
Date Acquired | 2005-11 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Market Place at Sea Colony, Bethany Beach, DE |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 2,920 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyNineMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 81 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyNineMember |  |  |  |
Basis at Close of Period, Land | 1,147 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyNineMember |  |  |  |
Basis at Close of Period, Building and Improvements | 1,854 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyNineMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyNineMember |  |  |  |
Total | 3,001 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyNineMember |  |  |  |
Accumulated Depreciation | 320 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyNineMember |  |  |  |
Book Value | 2,681 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyNineMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyThirtyNineMember |  |  |  |
Date Acquired | 2008-03 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Seven Corners, Falls Church, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 4,848 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 43,692 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyMember |  |  |  |
Basis at Close of Period, Land | 4,913 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyMember |  |  |  |
Basis at Close of Period, Building and Improvements | 43,627 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyMember |  |  |  |
Total | 48,540 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyMember |  |  |  |
Accumulated Depreciation | 25,486 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyMember |  |  |  |
Book Value | 23,054 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyMember |  |  |  |
Related Debt | 69,397 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyMember |  |  |  |
Date Acquired | 1973-07 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Seven Corners, Falls Church, VA | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1956 |  |  |  |
Shopping Centers | Seven Corners, Falls Church, VA | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1997 |  |  |  |
Shopping Centers | Severna Park Marketplace, Severna Park, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 63,254 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyOneMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 63 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyOneMember |  |  |  |
Basis at Close of Period, Land | 12,700 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyOneMember |  |  |  |
Basis at Close of Period, Building and Improvements | 50,617 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyOneMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyOneMember |  |  |  |
Total | 63,317 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyOneMember |  |  |  |
Accumulated Depreciation | 4,112 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyOneMember |  |  |  |
Book Value | 59,205 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyOneMember |  |  |  |
Related Debt | 35,125 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyOneMember |  |  |  |
Date Acquired | 2011-09 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Shops at Fairfax, Fairfax, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 2,708 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyTwoMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 9,898 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyTwoMember |  |  |  |
Basis at Close of Period, Land | 992 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyTwoMember |  |  |  |
Basis at Close of Period, Building and Improvements | 11,614 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyTwoMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyTwoMember |  |  |  |
Total | 12,606 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyTwoMember |  |  |  |
Accumulated Depreciation | 6,914 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyTwoMember |  |  |  |
Book Value | 5,692 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyTwoMember |  |  |  |
Related Debt | 6,160 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyTwoMember |  |  |  |
Date Acquired | 1975-06 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | Shops at Fairfax, Fairfax, VA | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1975 |  |  |  |
Shopping Centers | Shops at Fairfax, Fairfax, VA | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1999 |  |  |  |
Shopping Centers | Smallwood Village Center, Waldorf, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 17,819 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyThreeMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 7,618 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyThreeMember |  |  |  |
Basis at Close of Period, Land | 6,402 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyThreeMember |  |  |  |
Basis at Close of Period, Building and Improvements | 19,035 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyThreeMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyThreeMember |  |  |  |
Total | 25,437 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyThreeMember |  |  |  |
Accumulated Depreciation | 5,025 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyThreeMember |  |  |  |
Book Value | 20,412 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyThreeMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyThreeMember |  |  |  |
Date Acquired | 2006-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Southdale, Glen Burnie, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 3,650 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFourMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 20,919 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFourMember |  |  |  |
Basis at Close of Period, Land | 0 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFourMember |  |  |  |
Basis at Close of Period, Building and Improvements | 23,947 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFourMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 622 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFourMember |  |  |  |
Total | 24,569 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFourMember |  |  |  |
Accumulated Depreciation | 20,467 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFourMember |  |  |  |
Book Value | 4,102 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFourMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFourMember |  |  |  |
Date Acquired | 1972-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Southdale, Glen Burnie, MD | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1962 |  |  |  |
Shopping Centers | Southdale, Glen Burnie, MD | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1986 |  |  |  |
Shopping Centers | Southside Plaza, Richmond, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 6,728 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFiveMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 9,597 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFiveMember |  |  |  |
Basis at Close of Period, Land | 1,878 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFiveMember |  |  |  |
Basis at Close of Period, Building and Improvements | 14,447 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFiveMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFiveMember |  |  |  |
Total | 16,325 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFiveMember |  |  |  |
Accumulated Depreciation | 11,100 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFiveMember |  |  |  |
Book Value | 5,225 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFiveMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyFiveMember |  |  |  |
Date of Construction | 1958 |  |  |  |
Date Acquired | 1972-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | South Dekalb Plaza, Atlanta, GA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 2,474 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySixMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 3,899 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySixMember |  |  |  |
Basis at Close of Period, Land | 703 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySixMember |  |  |  |
Basis at Close of Period, Building and Improvements | 5,670 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySixMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySixMember |  |  |  |
Total | 6,373 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySixMember |  |  |  |
Accumulated Depreciation | 4,285 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySixMember |  |  |  |
Book Value | 2,088 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySixMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySixMember |  |  |  |
Date of Construction | 1970 |  |  |  |
Date Acquired | 1976-02 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Thruway, Winston-Salem, NC |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 4,778 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySevenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 23,157 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySevenMember |  |  |  |
Basis at Close of Period, Land | 5,496 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySevenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 22,334 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySevenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 105 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySevenMember |  |  |  |
Total | 27,935 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySevenMember |  |  |  |
Accumulated Depreciation | 13,715 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySevenMember |  |  |  |
Book Value | 14,220 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySevenMember |  |  |  |
Related Debt | 41,441 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortySevenMember |  |  |  |
Date Acquired | 1972-05 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Thruway, Winston-Salem, NC | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1955 |  |  |  |
Shopping Centers | Thruway, Winston-Salem, NC | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1965 |  |  |  |
Shopping Centers | Village Center, Centreville, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 16,502 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyEightMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 1,870 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyEightMember |  |  |  |
Basis at Close of Period, Land | 7,851 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyEightMember |  |  |  |
Basis at Close of Period, Building and Improvements | 10,521 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyEightMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyEightMember |  |  |  |
Total | 18,372 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyEightMember |  |  |  |
Accumulated Depreciation | 5,713 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyEightMember |  |  |  |
Book Value | 12,659 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyEightMember |  |  |  |
Related Debt | 14,535 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyEightMember |  |  |  |
Date of Construction | 1990 |  |  |  |
Date Acquired | 1993-08 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | Westview Village, Frederick, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 5,146 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyNineMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 22,292 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyNineMember |  |  |  |
Basis at Close of Period, Land | 5,153 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyNineMember |  |  |  |
Basis at Close of Period, Building and Improvements | 22,285 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyNineMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyNineMember |  |  |  |
Total | 27,438 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyNineMember |  |  |  |
Accumulated Depreciation | 4,245 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyNineMember |  |  |  |
Book Value | 23,193 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyNineMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFortyNineMember |  |  |  |
Date of Construction | 2009 |  |  |  |
Date Acquired | 2011-07 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Shopping Centers | White Oak, Silver Spring, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 6,277 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 5,311 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyMember |  |  |  |
Basis at Close of Period, Land | 4,649 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyMember |  |  |  |
Basis at Close of Period, Building and Improvements | 6,939 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyMember |  |  |  |
Total | 11,588 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyMember |  |  |  |
Accumulated Depreciation | 5,604 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyMember |  |  |  |
Book Value | 5,984 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyMember |  |  |  |
Related Debt | 25,639 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyMember |  |  |  |
Date Acquired | 1972-01 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Shopping Centers | White Oak, Silver Spring, MD | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1958 |  |  |  |
Shopping Centers | White Oak, Silver Spring, MD | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1967 |  |  |  |
Shopping Centers | Other Buildings / Improvements |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Cost Capitalized Subsequent to Acquisition | 115 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_OtherRealEstateMember |  |  |  |
Basis at Close of Period, Building and Improvements | 115 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_OtherRealEstateMember |  |  |  |
Total | 115 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_OtherRealEstateMember |  |  |  |
Accumulated Depreciation | 84 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_OtherRealEstateMember |  |  |  |
Book Value | 31 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_OtherRealEstateMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_ShoppingCentersMember / us-gaap_RealEstatePropertiesAxis = bfs_OtherRealEstateMember |  |  |  |
Mixed-Use Properties |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 45,179 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 333,883 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember |  |  |  |
Basis at Close of Period, Land | 26,858 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember |  |  |  |
Basis at Close of Period, Building and Improvements | 352,204 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember |  |  |  |
Total | 379,062 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember |  |  |  |
Accumulated Depreciation | 126,217 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember |  |  |  |
Book Value | 252,845 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember |  |  |  |
Related Debt | 177,769 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember |  |  |  |
Mixed-Use Properties | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 5 years |  |  |  |
Mixed-Use Properties | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 10 years |  |  |  |
Mixed-Use Properties | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date Three |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 5 years |  |  |  |
Mixed-Use Properties | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date Four |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 4 years |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 21,459 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyOneMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 27,945 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyOneMember |  |  |  |
Basis at Close of Period, Land | 3,756 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyOneMember |  |  |  |
Basis at Close of Period, Building and Improvements | 45,648 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyOneMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyOneMember |  |  |  |
Total | 49,404 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyOneMember |  |  |  |
Accumulated Depreciation | 31,663 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyOneMember |  |  |  |
Book Value | 17,741 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyOneMember |  |  |  |
Related Debt | 30,429 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyOneMember |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Minimum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 35 years |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Maximum |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1984 |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1986 |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Construction Three |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1990 |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Construction Four |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1998 |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Construction Five |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2000 |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Acquisition Date One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 1984-12 |  |  |  |
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Acquisition Date Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 1984-02 |  |  |  |
Mixed-Use Properties | Clarendon Center, Arlington, VA (1) |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 12,753 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyTwoMember | [1] |  |  |
Cost Capitalized Subsequent to Acquisition | 185,485 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyTwoMember | [1] |  |  |
Basis at Close of Period, Land | 16,287 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyTwoMember | [1] |  |  |
Basis at Close of Period, Building and Improvements | 181,951 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyTwoMember | [1] |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyTwoMember | [1] |  |  |
Total | 198,238 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyTwoMember | [1] |  |  |
Accumulated Depreciation | 21,709 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyTwoMember | [1] |  |  |
Book Value | 176,529 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyTwoMember | [1] |  |  |
Related Debt | 115,291 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyTwoMember | [1] |  |  |
Date of Construction | 2010 | [1] |  |  |
Mixed-Use Properties | Clarendon Center, Arlington, VA (1) | Acquisition Date One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 1973-07 | [1] |  |  |
Mixed-Use Properties | Clarendon Center, Arlington, VA (1) | Acquisition Date Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 1996-01 | [1] |  |  |
Mixed-Use Properties | Clarendon Center, Arlington, VA (1) | Acquisition Date Three |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2002-04 | [1] |  |  |
Mixed-Use Properties | Crosstown Business Center, Tulsa, OK |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 3,454 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyThreeMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 6,358 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyThreeMember |  |  |  |
Basis at Close of Period, Land | 604 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyThreeMember |  |  |  |
Basis at Close of Period, Building and Improvements | 9,208 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyThreeMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyThreeMember |  |  |  |
Total | 9,812 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyThreeMember |  |  |  |
Accumulated Depreciation | 6,792 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyThreeMember |  |  |  |
Book Value | 3,020 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyThreeMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyThreeMember |  |  |  |
Date of Construction | 1974 |  |  |  |
Date Acquired | 1975-10 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 40 years |  |  |  |
Mixed-Use Properties | 601 Pennsylvania Ave., Washington, DC |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 5,479 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyFourMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 62,169 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyFourMember |  |  |  |
Basis at Close of Period, Land | 5,667 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyFourMember |  |  |  |
Basis at Close of Period, Building and Improvements | 61,981 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyFourMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyFourMember |  |  |  |
Total | 67,648 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyFourMember |  |  |  |
Accumulated Depreciation | 46,500 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyFourMember |  |  |  |
Book Value | 21,148 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyFourMember |  |  |  |
Related Debt | 0 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyFourMember |  |  |  |
Date of Construction | 1986 |  |  |  |
Date Acquired | 1973-07 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 35 years |  |  |  |
Mixed-Use Properties | Washington Square, Alexandria, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 2,034 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySixMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 51,926 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySixMember |  |  |  |
Basis at Close of Period, Land | 544 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySixMember |  |  |  |
Basis at Close of Period, Building and Improvements | 53,416 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySixMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySixMember |  |  |  |
Total | 53,960 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySixMember |  |  |  |
Accumulated Depreciation | 19,553 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySixMember |  |  |  |
Book Value | 34,407 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySixMember |  |  |  |
Related Debt | 32,049 us-gaap_SecuredDebt / us-gaap_MajorPropertyClassAxis = bfs_MixedUsePropertiesMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySixMember |  |  |  |
Date Acquired | 1973-07 |  |  |  |
Buildings and Improvements Depreciable Lives in Years | 50 years |  |  |  |
Mixed-Use Properties | Washington Square, Alexandria, VA | Construction One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 1952 |  |  |  |
Mixed-Use Properties | Washington Square, Alexandria, VA | Construction Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date of Construction | 2000 |  |  |  |
Development Land |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 9,622 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 2,003 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember |  |  |  |
Basis at Close of Period, Land | 11,625 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember |  |  |  |
Basis at Close of Period, Building and Improvements | 24,755 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember |  |  |  |
Total | 36,380 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember |  |  |  |
Book Value | 36,380 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember |  |  |  |
Development Land, Related Debt | 5,391 us-gaap_ConstructionLoan / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember |  |  |  |
Development Land | Ashland Square Phase II, Manassas, VA |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 5,292 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySevenMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 1,717 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySevenMember |  |  |  |
Basis at Close of Period, Land | 7,009 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySevenMember |  |  |  |
Basis at Close of Period, Building and Improvements | 0 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySevenMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySevenMember |  |  |  |
Total | 7,009 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySevenMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySevenMember |  |  |  |
Book Value | 7,009 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySevenMember |  |  |  |
Development Land, Related Debt | 0 us-gaap_ConstructionLoan / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftySevenMember |  |  |  |
Date Acquired | 2004-12 |  |  |  |
Development Land | New Market, New Market, MD |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 2,088 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyEightMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 286 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyEightMember |  |  |  |
Basis at Close of Period, Land | 2,374 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyEightMember |  |  |  |
Basis at Close of Period, Building and Improvements | 0 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyEightMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyEightMember |  |  |  |
Total | 2,374 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyEightMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyEightMember |  |  |  |
Book Value | 2,374 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyEightMember |  |  |  |
Development Land, Related Debt | 0 us-gaap_ConstructionLoan / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_RealEstatePropertyFiftyEightMember |  |  |  |
Date Acquired | 2005-09 |  |  |  |
Development Land | Park Van Ness, Washington, DC |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Initial Basis | 2,242 bfs_RealEstateInvestmentPropertyCostInitialBasis / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_ParkVanNessMember |  |  |  |
Cost Capitalized Subsequent to Acquisition | 0 bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_ParkVanNessMember |  |  |  |
Basis at Close of Period, Land | 2,242 us-gaap_LandAndLandImprovements / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_ParkVanNessMember |  |  |  |
Basis at Close of Period, Building and Improvements | 24,755 us-gaap_BuildingsAndImprovementsGross / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_ParkVanNessMember |  |  |  |
Basis at Close of Period, Leasehold Interests | 0 us-gaap_RealEstateInvestmentsOther / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_ParkVanNessMember |  |  |  |
Total | 26,997 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_ParkVanNessMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_ParkVanNessMember |  |  |  |
Book Value | 26,997 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_ParkVanNessMember |  |  |  |
Development Land, Related Debt | $ 5,391 us-gaap_ConstructionLoan / us-gaap_MajorPropertyClassAxis = bfs_DevelopmentLandMember / us-gaap_RealEstatePropertiesAxis = bfs_ParkVanNessMember |  |  |  |
Development Land | Park Van Ness, Washington, DC | Development Date One |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 1973-07 |  |  |  |
Development Land | Park Van Ness, Washington, DC | Development Date Two |  |  |  |  |
Real Estate Properties [Line Items] |  |  |  |  |
Date Acquired | 2011-02 |  |  |  |
[1] | Includes the North and South Blocks and Residential

X
- Definition Acquisition Date + References No definition available. + Details
Name: | bfs_AcquisitionDate
Namespace Prefix: | bfs_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date of Construction + References No definition available. + Details
Name: | bfs_DateOfConstruction
Namespace Prefix: | bfs_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Real Estate Investment Property Cost, Capitalized Subsequent To Acquisition + References No definition available. + Details
Name: | bfs_RealEstateInvestmentPropertyCostCapitalizedSubsequentToAcquisition
Namespace Prefix: | bfs_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Real Estate Investment Property Cost, Initial Basis + References No definition available. + Details
Name: | bfs_RealEstateInvestmentPropertyCostInitialBasis
Namespace Prefix: | bfs_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Secured Debt, Including Construction Loan + References No definition available. + Details
Name: | bfs_SecuredDebtIncludingConstructionLoan
Namespace Prefix: | bfs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 4 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6812-107765 + Details
Name: | us-gaap_BuildingsAndImprovementsGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This element represents the carrying value of a short-term real estate loan to finance building costs. The funds are disbursed as needed or in accordance with a prearranged plan; generally, a portion of the funds is disbursed at inception and the remainder as construction progresses. The money is repaid on completion of the project, usually from the proceeds of a mortgage loan. The rate is normally higher than the prime rate, and there is usually an origination fee. The effective yield on these loans tends to be high, and the lender has a security interest in the real property. Note that there are separate concepts for the current and noncurrent portions of long-term construction loans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20 -Article 5 + Details
Name: | us-gaap_ConstructionLoan
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before accumulated deprecation and depletion of real estate held for productive use and additions or improvements to real estate held for productive use, examples include, but are not limited to, walkways, driveways, fences, and parking lots. Excludes land held for sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6812-107765 + Details
Name: | us-gaap_LandAndLandImprovements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- 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
Name: | us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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
Name: | us-gaap_RealEstateInvestmentPropertyAtCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of real estate investment property, net of accumulated depreciation, 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
Name: | us-gaap_RealEstateInvestmentPropertyNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of real estate owned for income production and capital accretion potential, not otherwise specified in the existing taxonomy. Such real estate excludes that which is occupied or used in the business, for entertainment purposes, or held in inventory for specific 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(d)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_RealEstateInvestmentsOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_RealEstatePropertiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower. + 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 210.9-03.16) -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 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 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 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_SecuredDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_MajorPropertyClassAxis=bfs_DevelopmentLandMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorPropertyClassAxis=bfs_MixedUsePropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorPropertyClassAxis=bfs_ShoppingCentersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |