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Investment in Unconsolidated Real Estate Ventures - Investment in Real Estate Ventures and Share of Real Estate Ventures' Income (Loss) (Parenthetical) (Details) $ in Thousands |  | 12 Months Ended |  |  |  |  |  |
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Mar. 02, 2016 USD ($) option term | Dec. 31, 2016 USD ($) | Sep. 22, 2016 | Jun. 30, 2016 | Dec. 31, 2015 USD ($) | Jun. 22, 2015 | Dec. 20, 2011 | Jan. 20, 2011
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Notional amount |  |  | $ 328,610 |  |  |  | $ 328,610 |  |  |
Equity Method Investment Summarized Financial Information Debt |  |  | $ 997,466 |  |  |  | 794,571 |  |  |
Brandywine - Al Venture [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Equity method investment percentage |  |  | 50.00% | [1],[2] |  |  |  |  | 50.00% |
Debt Instrument, Interest Rate, Effective Percentage | [2] |  | 3.96% |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt | [2] |  | $ 131,539 |  |  |  | 132,717 |  |  |
HSRE BDN I, LLC [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Equity method investment percentage | [1],[3] |  | 50.00% |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt | [3] |  | $ 105,000 |  |  |  | 95,562 |  |  |
Austin Joint Venture [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Equity method investment percentage | [1],[4] |  | 50.00% |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage | [4] |  | 3.36% |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt | [4] |  | $ 405,734 |  |  |  | 410,066 |  |  |
MAP Venture [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Equity method investment percentage | [1],[5] |  | 50.00% |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt | [5] |  | $ 180,800 |  |  |  | 0 |  |  |
PJP V [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Equity method investment percentage |  |  |  |  | 25.00% |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt | [6] |  | 0 |  |  |  | 5,035 |  |  |
1000 Chesterbrook Blvd. [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Equity method investment percentage |  |  |  |  |  | 50.00% |  |  |  |
Equity Method Investment Summarized Financial Information Debt | [6] |  | 0 |  |  |  | 23,610 |  |  |
Broadmoor Austin Associates [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Percentage of ownership interests |  |  |  |  |  |  |  | 50.00% |  |
Equity Method Investment Summarized Financial Information Debt | [6] |  | $ 0 |  |  |  | 0 |  |  |
Brandywine Nineteen Nineteen Ventures [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Equity method investment percentage |  |  | 50.00% | [1],[4],[7] |  |  |  |  |  | 50.00%
Debt Instrument, Interest Rate Terms |  |  | LIBOR + 2.00 |  |  |  |  |  |  |
Interest rate protection cap |  |  | 4.50% |  |  |  |  |  |  |
Interest rate upon 90% residential occupancy and commencement of lease in retail space |  |  | 1.75% |  |  |  |  |  |  |
Percentage of residential occupancy and commencement of lease in retail space |  |  | 90.00% |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt | [4],[7] |  | $ 79,250 |  |  |  | 19,411 |  |  |
Seven Tower Bridge [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Equity method investment percentage | [1] |  | 20.00% |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage |  |  | 3.71% |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt |  |  | $ 14,710 |  |  |  | $ 14,789 |  |  |
Secured JV Debt [Member] | Brandywine - Al Venture [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Number of Fixed Rate Mortgages |  |  | 3 |  |  |  |  |  |  |
Secured JV Debt [Member] | Brandywine - Al Venture [Member] | Fixed rate loan maturing January 1, 2019 [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 37,900 |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 4.40% |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Jan. 01, 2019 |  |  |  |  |  |  |
Secured JV Debt [Member] | Brandywine - Al Venture [Member] | Fixed rate loan maturing January 1, 2022 [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 27,100 |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 4.65% |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Jan. 01, 2022 |  |  |  |  |  |  |
Secured JV Debt [Member] | Brandywine - Al Venture [Member] | Fixed rate loan maturing August 1, 2019 [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 66,500 |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 3.22% |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Aug. 01, 2019 |  |  |  |  |  |  |
Long-term Debt, Weighted Average Interest Rate |  |  | 3.96% |  |  |  |  |  |  |
Secured JV Debt [Member] | HSRE BDN I, LLC [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Equity method investment percentage |  | 50.00% |  |  |  |  |  |  |  |
Secured JV Debt [Member] | Austin Joint Venture [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Number of Mortgages |  |  | 7 |  |  |  |  |  |  |
Secured JV Debt [Member] | Austin Joint Venture [Member] | First mortgage - swapped to fixed [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 33,900 |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Nov. 01, 2018 |  |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  | 1.59% |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage |  |  | 3.52% |  |  |  |  |  |  |
Derivative, Basis Spread on Variable Rate |  |  | 1.93% |  |  |  |  |  |  |
Secured JV Debt [Member] | Austin Joint Venture [Member] | Second mortgage - swapped to fixed [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 54,700 |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Oct. 15, 2018 |  |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  | 1.49% |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage |  |  | 3.19% |  |  |  |  |  |  |
Derivative, Basis Spread on Variable Rate |  |  | 1.70% |  |  |  |  |  |  |
Secured JV Debt [Member] | Austin Joint Venture [Member] | Third mortgage - swapped to fixed [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 137,000 |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Nov. 01, 2018 |  |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  | 1.43% |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage |  |  | 3.44% |  |  |  |  |  |  |
Derivative, Basis Spread on Variable Rate |  |  | 2.01% |  |  |  |  |  |  |
Secured JV Debt [Member] | Austin Joint Venture [Member] | Fourth mortgage - swapped to fixed [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 29,000 |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 4.50% |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Apr. 06, 2019 |  |  |  |  |  |  |
Secured JV Debt [Member] | Austin Joint Venture [Member] | Fifth mortgage - swapped to fixed [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 34,300 |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 3.87% |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Aug. 06, 2019 |  |  |  |  |  |  |
Secured JV Debt [Member] | Austin Joint Venture [Member] | Sixth mortgage - swapped to fixed [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 86,700 |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Feb. 10, 2020 |  |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  | 1.36% |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage |  |  | 3.36% |  |  |  |  |  |  |
Derivative, Basis Spread on Variable Rate |  |  | 2.00% |  |  |  |  |  |  |
Secured JV Debt [Member] | Austin Joint Venture [Member] | Seventh mortgage - swapped to fixed [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  | $ 30,000 |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Jan. 01, 2021 |  |  |  |  |  |  |
Long-term Debt, Weighted Average Interest Rate |  |  | 3.36% |  |  |  |  |  |  |
Debt Instrument, Interest Rate Terms |  |  | LIBOR + 1.85 |  |  |  |  |  |  |
Interest rate protection cap |  |  | 2.75% |  |  |  |  |  |  |
Secured JV Debt [Member] | MAP Venture [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Feb. 09, 2018 |  |  |  |  |  |  |
Interest rate protection cap |  | 1.75% |  |  |  |  |  |  |  |
Notional amount |  | $ 200,800 |  |  |  |  |  |  |  |
Debt instrument, number of options to extend maturity date | option |  | 3 |  |  |  |  |  |  |  |
Debt instrument, number of successive terms | term |  | 3 |  |  |  |  |  |  |  |
Secured JV Debt [Member] | Seven Tower Bridge [Member] | Mortgage Maturing March 2017 [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 7.00% |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Mar. 01, 2017 |  |  |  |  |  |  |
Debt Instrument, Number of Fixed Rate Mortgages |  |  | 2 |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt |  |  | $ 8,000 |  |  |  |  |  |  |
Secured JV Debt [Member] | Seven Tower Bridge [Member] | Fixed Rate Loan Maturing September 2025 [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 3.00% |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Sep. 01, 2025 |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt |  |  | $ 800 |  |  |  |  |  |  |
Secured JV Debt [Member] | Seven Tower Bridge [Member] | Fixed Rate Loan Maturing February 2017 [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 4.00% |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Feb. 07, 2017 |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt |  |  | $ 2,000 |  |  |  |  |  |  |
Secured JV Debt [Member] | Seven Tower Bridge [Member] | Fixed Rate Loan Maturing March 2020 [Member] |  |  |  |  |  |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 3.25% |  |  |  |  |  |  |
Debt Instrument Maturity Date |  |  | Mar. 11, 2020 |  |  |  |  |  |  |
Long-term Debt, Weighted Average Interest Rate |  |  | 3.42% |  |  |  |  |  |  |
Equity Method Investment Summarized Financial Information Debt |  |  | $ 3,900 |  |  |  |  |  |  |
[1] | Ownership percentage represents the Company’s entitlement to residual distributions after payments of priority returns, where applicable.
[2] | See “Brandywine AI Venture: 3141 Fairview Park Drive” section below for information discussing activity that occurred during 2016 relating to this venture.
[3] | 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). The Company increased its ownership interest in the HSRE-BDN I, LLC venture (also referred to as the “Evo at Cira South Venture”) to 50% on March 2, 2016. On June 10, 2016, HSRE-BDN I, LLC refinanced its debt. See “Evo at Cira South Venture” section below for further details on these transactions
[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). The Company increased its ownership interest in the HSRE-BDN I, LLC venture (also referred to as the “Evo at Cira South Venture”) to 50% on March 2, 2016. On June 10, 2016, HSRE-BDN I, LLC refinanced its debt. See “Evo at Cira South Venture” section below for further details on these transactions.
[5] | In order to fulfill interest rate protection requirements, a LIBOR interest rate cap of 1.75% was purchased, effective February 3, 2016 and maturing February 9, 2018, for a notional amount of $200.8 million. There are three options to extend the maturity date of the debt for three successive terms, each year representing a separate option.
[6] | The Company liquidated its 25% ownership interest in the PJP V real estate venture on September 22, 2016. On June 30, 2016, the Company liquidated its 50% ownership interest in the venture known as 1000 Chesterbrook. The ownership interest in Invesco, L.P. was sold prior to December 31, 2015, and on August 19, 2016, the Company assigned its residual profits interest to the general partner of Invesco. The Company purchased the remaining 50% interest in Broadmoor Austin Associates on June 22, 2015. The ownership interest in Residence Inn Tower Bridge was sold on December 30, 2015. See below for further detail on 2016 dispositions.
[7] | The stated rate for the construction loan is LIBOR + 2.00%. It is further reduced to 1.75% upon reaching 90% residential occupancy and commencement of the lease in the retail space. To fulfill interest rate protection requirements, an interest rate cap was purchased at 4.50%.

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