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Investment in Unconsolidated Ventures (Textual) (Details) $ in Thousands |  |  |  |  |  |  |  |  |  |  |  | 12 Months Ended |  |  |  |  |
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Dec. 30, 2015 USD ($) | May. 29, 2015 USD ($) a | Jan. 30, 2015 USD ($) | Oct. 21, 2014 USD ($) | Oct. 17, 2014 USD ($) ft² property | Jul. 31, 2014 USD ($) ft² property Storey | Apr. 03, 2014 USD ($) ft² property Storey | Feb. 19, 2014 USD ($) ft² Floor | Oct. 16, 2013 USD ($) ft² property | Jul. 31, 2013 USD ($) ft² a | Jun. 19, 2013 USD ($) | Dec. 31, 2015 USD ($) ft² a property Storey Real_Estate_Ventures Building Apartment_unit | Dec. 31, 2014 USD ($) ft² property | Dec. 31, 2013 USD ($) ft² property Storey | Dec. 31, 2011 USD ($) | Jun. 22, 2015 | Mar. 26, 2013 USD ($) | Jan. 25, 2013 USD ($) a Storey Bed | Jan. 20, 2011 a | Dec. 19, 2007 ft² property
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of unconsolidated investments in Real Estate Ventures | Real_Estate_Ventures |  |  |  |  |  |  |  |  |  |  |  |  | 16 |  |  |  |  |  |  |  |  |  |
Equity Method Investments including net liabilities |  |  |  |  |  |  |  |  |  |  |  |  | $ 239,874 |  | $ 223,790 |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) |  |  |  |  |  |  |  |  |  |  |  |  | $ 241,004 |  | 225,004 |  | $ 180,512 |  |  |  |  |  |
Number of negative investment real estate ventures | Real_Estate_Ventures |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  |  |  |  |  | 4,300,000 |  |  |  |  |  |  |  |  |  |
Number of real estate ventures that owns undeveloped land | Real_Estate_Ventures |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |
Area owned by real estate venture of undeveloped parcels of land | a |  |  |  |  |  |  |  |  |  |  |  |  | 4.3 |  |  |  |  |  |  |  |  |  |
Number of real estate ventures that owns land under development | Real_Estate_Ventures |  |  |  |  |  |  |  |  |  |  |  |  | 3 |  |  |  |  |  |  |  |  |  |
Area owned by real estate venture in parcels of land under development | a |  |  |  |  |  |  |  |  |  |  |  |  | 2.2 |  |  |  |  |  |  |  |  |  |
Number of real estate Investments in residential towers | Real_Estate_Ventures |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |
Number of apartment units in a real estate Venture | Apartment_unit |  |  |  |  |  |  |  |  |  |  |  |  | 345 |  |  |  |  |  |  |  |  |  |
Number of real estate investments in apartment complex | Real_Estate_Ventures |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |
Number of apartment complex in a real estate Venture | Apartment_unit |  |  |  |  |  |  |  |  |  |  |  |  | 398 |  |  |  |  |  |  |  |  |  |
Minimum percentage of unconsolidated equity method investment ownership |  |  |  |  |  |  |  |  |  |  |  |  | 20.00% |  |  |  |  |  |  |  |  |  |
Maximum percentage of unconsolidated equity method investment ownership |  |  |  |  |  |  |  |  |  |  |  |  | 70.00% |  |  |  |  |  |  |  |  |  |
Ownership percentage | [1] |  |  |  |  |  |  |  |  |  |  |  | 0.00% |  |  |  |  |  |  |  |  |  |
Proceeds from Equity Method Investment, Dividends or Distributions |  |  |  |  |  |  |  |  |  |  |  |  | $ 6,100 |  | 0 |  | 16,963 |  |  |  |  |  |
Carrying value of assets |  |  |  |  |  |  |  |  |  |  |  |  | $ 422,900 |  |  |  |  |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  |  |  |  |  |  |  |  | 179 |  |  |  |  |  |  |  |  |  |
Net gain on sale of undepreciated real estate |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  | 8,212 |  | 0 |  |  |  |  |  |
Acquisition of properties |  |  |  |  |  |  |  |  |  |  |  |  | 150,472 |  | 18,443 |  | 161,604 |  |  |  |  |  |
Proceeds from repayment of mortgage notes receivable |  |  |  |  |  |  |  |  |  |  |  |  | 88,000 |  | 7,026 |  | 200 |  |  |  |  |  |
Payments to Acquire Equity Method Investments |  |  |  |  |  |  |  |  |  |  |  |  | 68,549 |  | 46,098 |  | 33,069 |  |  |  |  |  |
Net gain from remeasurement of investments in real estate ventures |  |  |  |  |  |  |  |  |  |  |  |  | 758 |  | 458 |  | 6,866 |  |  |  |  |  |
Net gain on real estate venture transactions |  |  |  |  |  |  |  |  |  |  |  |  | 7,418 |  | $ (417) |  | $ 3,683 |  |  |  |  |  |
TB-BDN Plymouth Apartments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Guarantor obligations, current carrying value |  |  |  |  |  |  |  |  |  |  |  |  | 3,200 |  |  |  |  |  |  |  |  |  |
1919 Venture [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Guarantor obligations, current carrying value |  |  |  |  |  |  |  |  |  |  |  |  | $ 88,900 |  |  |  |  |  |  |  |  |  |
Encino Trace - Land [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  | 320,000 |  |  |  | 320,000 |  |  |  |  |  |  |  |  |  |
Payments to Acquire Land |  |  |  |  |  |  |  |  | $ 14,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |
Number of floors of a building |  |  |  |  |  |  |  |  | 4 |  |  |  | 4 |  |  |  |  |  |  |  |  |  |
Office Building [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  |  |  |  |  | 2,649,926 |  | 645,273 |  | 2,472,036 |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  |  |  |  |  |  |  |  | 27 |  | 8 |  | 21 |  |  |  |  |  |
Four Points Centre [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 192,396 |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |
Number of floors of a building | Storey |  |  |  |  |  |  |  | 3 |  |  |  |  |  |  |  |  | 3 |  |  |  |  |  |
Four Points Centre [Member] | Office Building [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 192,396 |  |  |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |
Brandywine Realty Trust [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |
Coppell Associates [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) | [2] |  |  |  |  |  |  |  |  |  |  |  | $ 1,130 |  | $ 1,214 |  |  |  |  |  |  |  |
Ownership percentage | [1],[2] |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |
Real Estate Ventures Owned Office Buildings [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of real estate ventures that owns buildings | Real_Estate_Ventures |  |  |  |  |  |  |  |  |  |  |  |  | 9 |  |  |  |  |  |  |  |  |  |
Number of office buildings in Real Estate Ventures | Building |  |  |  |  |  |  |  |  |  |  |  |  | 31 |  |  |  |  |  |  |  |  |  |
Residence Inn Tower Bridge [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) |  | $ 900 |  |  |  |  |  |  |  |  |  |  | $ 0 | [3] | 723 | [3] |  |  |  |  |  |  |
Ownership percentage |  | 50.00% |  |  |  |  |  |  |  |  |  |  | 0.00% | [1],[3] |  |  |  |  |  |  |  |  |
Proceeds from Equity Method Investment, Dividends or Distributions |  | $ 6,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gain on sale of its interest in the real estate venture |  | $ 5,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
51 N 50 Patterson [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) |  |  |  |  |  |  |  |  |  |  |  |  | $ 16,725 |  | 0 |  |  |  |  |  |  |  |
Area owned by real estate venture of undeveloped parcels of land | a |  |  | 0.9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  | 70.00% |  |  |  |  |  |  |  |  |  | 70.00% | [1] |  |  |  |  |  |  |  |  |
Payments to Acquire Land |  |  | $ 15,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
51 N 50 Patterson [Member] | JBG [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  | 30.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Land |  |  | $ 6,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
1250 First Street Office [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) |  |  |  |  |  |  |  |  |  |  |  |  | $ 14,312 |  | 0 |  |  |  |  |  |  |  |
Area owned by real estate venture of undeveloped parcels of land | a |  |  | 0.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  | 70.00% |  |  |  |  |  |  |  |  |  | 70.00% | [1] |  |  |  |  |  |  |  |  |
Payments to Acquire Land |  |  | $ 13,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
1250 First Street Office [Member] | JBG [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  | 30.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Land |  |  | $ 5,700 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
25 M Street [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value of assets |  |  |  |  |  |  |  |  |  |  |  |  | $ 20,500 |  |  |  |  |  |  |  |  |  |
GI Interchange Office LLC (DRA — N. PA) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) | [3] |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  | 0 |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,611,961
Ownership percentage | [1],[3] |  |  |  |  |  |  |  |  |  |  |  | 0.00% |  |  |  |  |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 29
GI Interchange Office LLC (DRA — N. PA) [Member] | Brandywine Realty Trust [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 20.00%
Brandywine Nineteen Nineteen Ventures [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) | [4],[5] |  |  |  |  |  |  |  |  |  |  |  | $ 29,086 |  | 12,823 |  |  |  |  |  |  |  |
Area owned by real estate venture of undeveloped parcels of land | a |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |
Ownership percentage |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% | [1],[4],[5] |  |  |  |  |  |  |  | 50.00% |
Payments to Acquire Land |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 9,300 |  |  |  |  |
Brandywine Nineteen Nineteen Ventures [Member] | LCOR/Calstrs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate gross sales price of a joint venture |  |  |  |  | $ 16,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
General Partners' Contributed Capital |  |  |  |  | 5,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net gain on sale of undepreciated real estate |  |  |  |  | $ 8,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding construction loan |  |  |  |  |  |  |  |  |  |  |  |  | $ 19,400 |  |  |  |  |  |  |  |  |  |
Equity method investments, Cash contributions |  |  |  |  |  |  |  |  |  |  |  |  | 29,600 |  |  |  |  |  |  |  |  |  |
Austin Joint Venture [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) | [4] |  |  |  |  |  |  |  |  |  |  |  | $ 60,427 |  | 40,374 |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  | 590,881 | 232,274 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage | [1],[4] |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |
Number of Properties | property |  |  |  |  |  | 7 | 2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investments, Cash contributions |  |  |  |  |  | $ 18,900 | $ 12,800 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investments, Closing costs |  |  |  |  |  | 200 | 100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investment, Consideration transferred |  |  |  |  |  |  | 48,200 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Mortgage loans outstanding |  |  |  |  |  |  | $ 34,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Mortgage loans interest rate |  |  |  |  |  |  | 3.87% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investments Purchase Adjustments |  |  |  |  |  |  | $ 900 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business acquisition cost of acquired entity transaction costs borne by seller |  |  |  |  |  |  | 600 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisition of properties |  |  |  |  |  | 128,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Short-term Bank Loans and Notes Payable |  |  |  |  |  | $ 88,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Austin Joint Venture [Member] | Four Points Centre [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-Recourse Debt |  |  |  |  |  |  |  | $ 29,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Austin Joint Venture [Member] | Four Points Centre [Member] | Office Building [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rentable Square Feet | ft² |  |  |  |  |  |  |  | 192,396 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Austin Joint Venture [Member] | Brandywine Realty Trust [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |
Aggregate gross sales price of a joint venture |  |  |  |  |  |  |  |  |  | $ 330,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investments, Cash contributions |  |  |  |  |  |  | $ 6,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of properties contributed to a joint venture | property |  |  |  |  |  |  |  |  |  | 7 |  |  |  |  |  |  |  |  |  |  |  |  |
Area of Real Estate Property | ft² |  |  |  |  |  |  |  |  |  | 1,398,826 |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investment, agreement to pay future capital expenditures |  |  |  |  |  |  |  |  |  | $ 5,200 |  |  |  |  |  |  | $ 800 |  |  |  |  |  |
Equity Method Investment, Additional Distribution Rights |  |  |  |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |  |  |  |  |  |
Net gain (loss) on real estate venture transactions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25,900 |  |  |  |  |  |
Austin Joint Venture [Member] | Brandywine Realty Trust [Member] | Four Points Centre [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aggregate gross sales price of a joint venture |  |  |  |  |  |  |  | $ 41,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount Of Participant Contribution |  |  |  |  |  |  |  | 5,900 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from Equity Method Investment, Dividends or Distributions |  |  |  |  |  |  |  | $ 34,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Austin Joint Venture [Member] | DRA Advisors LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Distribution, Net of Initial Funding Agreement |  |  |  |  |  |  |  |  |  | 266,300 |  |  |  |  |  |  |  |  |  |  |  |  |
Amount Of Participant Contribution |  |  |  |  |  |  |  |  |  | 49,700 |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investments, Closing costs |  |  |  |  |  |  |  |  |  | 1,900 |  |  |  |  |  |  |  |  |  |  |  |  |
Closing Prorations and Lender Holdbacks |  |  |  |  |  |  |  |  |  | 6,900 |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from Equity Method Investment, Dividends or Distributions |  |  |  |  |  |  |  |  |  | 271,500 |  |  |  |  |  |  |  |  |  |  |  |  |
Non-Recourse Debt |  |  |  |  |  |  |  |  |  | $ 230,600 |  |  |  |  |  |  |  |  |  |  |  |  |
Austin, Texas [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of floors of a building | Storey |  |  |  |  |  |  | 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Austin, Texas [Member] | Brandywine Realty Trust [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity method investment, agreement to pay future capital expenditures |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,400 |  |  |  |  |  |  |  |
River Place [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from repayment of mortgage notes receivable |  |  |  | $ 88,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
4040 Wilson Venture [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) |  |  |  |  |  |  |  |  |  |  |  |  | $ 36,626 |  | 27,415 |  |  |  |  |  |  |  |
Area owned by real estate venture of undeveloped parcels of land | a |  |  |  |  |  |  |  |  |  |  | 1.3 |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage | [1] |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |
Area of Real Estate Property | ft² |  |  |  |  |  |  |  |  |  |  | 426,900 |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Budgeted Total Project Cost |  |  |  |  |  |  |  |  |  |  | $ 194,600 |  |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Equity Method Investments |  |  |  |  |  |  |  |  |  |  | 72,000 |  |  |  |  |  |  |  |  |  |  |  |
4040 Wilson Venture [Member] | Brandywine Realty Trust [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Interest in Joint Venture |  |  |  |  |  |  |  |  |  |  | 36,000 |  | $ 35,600 |  |  |  |  |  |  |  |  |  |
4040 Wilson Venture [Member] | Ashton Park [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of land, net of amount encumbered |  |  |  |  |  |  |  |  |  |  | $ 36,000 |  |  |  |  |  |  |  |  |  |  |  |
Six Tower Bridge [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net gain from remeasurement of investments in real estate ventures |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,800 |  |  |  |  |  |
Fair Value of Contingent Consideration |  |  |  |  |  |  |  |  |  |  |  | $ 24,500 |  |  |  |  |  |  |  |  |  |  |
Business Acquisition Purchase Price Allocation Building |  |  |  |  |  |  |  |  |  |  |  | 14,800 |  |  |  |  |  |  |  |  |  |  |
Business Acquisition Purchase Price Allocation Land Portion |  |  |  |  |  |  |  |  |  |  |  | 6,900 |  |  |  |  |  |  |  |  |  |  |
Business Acquisition Purchase Price Allocation Intangible Assets |  |  |  |  |  |  |  |  |  |  |  | 3,300 |  |  |  |  |  |  |  |  |  |  |
Business Acquisition Purchase Price Allocated To Market Lease Liabilities |  |  |  |  |  |  |  |  |  |  |  | 500 |  |  |  |  |  |  |  |  |  |  |
Two Tower Bridge [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) |  |  |  |  |  |  |  |  |  |  |  | (100) |  |  |  |  |  |  |  |  |  |  |
Investments, Fair Value Disclosure |  |  |  |  |  |  |  |  |  |  |  | $ 3,600 |  |  |  |  |  |  |  |  |  |  |
Net gain on real estate venture transactions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,700 |  |  |  |  |  |
The Grove at Cira Centre South [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of floors of a building | Storey |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 33 |  |
Student housing bed capacity | Bed |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 850 |  |
Area of developed parcels of land (in acres) owned by a Real Estate Venture | a |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  |
Equity Method Investment, Underlying Equity in Net Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 8,500 |  |
Guarantor obligations, current carrying value |  |  |  |  |  |  |  |  |  |  |  |  | 24,700 |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Aggregate Cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,000 |  |
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,500 |  |
The Grove at Cira Centre South [Member] | Campus Crest Properties, LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 30.00% |  |
The Grove at Cira Centre South [Member] | HSRE, LLC [Member] [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 40.00% |  |
BDN Beacon Venture LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 17,000 |  |  |
Ownership percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 20.00% |  |  |
PJP VII [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Company's share of equity (Company's basis) |  |  |  |  |  |  |  |  |  |  |  |  | $ 872 |  | $ 911 |  |  |  |  |  |  |  |
Ownership percentage | [1] |  |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |  |  |
Guarantor obligations, current carrying value |  |  |  |  |  |  |  |  |  |  |  |  | $ 500 |  |  |  |  |  |  |  |  |  |
[1] | Ownership percentage represents the Company’s entitlement to residual distributions after payments of priority returns, where applicable.
[2] | Carrying amount represents the negative investment balance of the venture and is included in other liabilities.
[3] | The ownership interest in Invesco, L.P. was sold prior to December 31, 2014. The Company purchased the remaining 50% interest in Broadmoor Austin Associates on June 22, 2015. The ownership interest in DRA-N. PA was disposed of on August 12, 2015. The ownership interest in Residence Inn Tower Bridge was sold on December 30, 2015. See below for further detail on 2015 dispositions.
[4] | The basis differences associated with these ventures are allocated between cost and the underlying equity in the net assets of the investee and is accounted for as if the entity were consolidated (i.e., allocated to the Company’s relative share of assets and liabilities with an adjustment to recognize equity in earnings for the appropriate depreciation/amortization).
[5] | The stated rate for the construction loan is LIBOR + 2.25%. The interest rate spread decreases to 2.00% upon receipt of certificate of occupancy. It is further reduced to 1.75% upon stabilization. To fulfill interest rate protection requirements an interest rate cap was purchased at 4.50%.

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- Definition Fair value at acquisition-date of the equity interest in the acquiree held by the acquirer, immediately before the acquisition date for businesses combined in stages. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g)(1) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
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- Definition This item represents the entity's ownership percentage in the investee multiplied by the investee's total equity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
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- Definition This element represents the current and noncurrent portions of a long-term real estate loan with an initial maturity beyond one year or beyond the normal operating cycle, if longer, 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 (generally one to seven years), 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. + 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 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19,20,22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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