Investment in Unconsolidated Real Estate Ventures - Summary of Results of Operations of Real Estate Ventures with Interests (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule Of Equity Method Investments [Line Items]
Equity in loss of Real Estate Ventures		$ (7,254)	$ (1,093)	$ (9,323)	$ (1,835)
Unconsolidated Real Estate Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Revenue		57,710	37,076	157,641	126,424
Operating expenses		(27,592)	(16,917)	(81,347)	(54,581)
Provision for impairment	[1]	(10,476)	0	(10,476)	0
Interest expense, net		(12,102)	(7,936)	(32,019)	(27,918)
Depreciation and amortization		(22,722)	(15,681)	(63,125)	(52,218)
Net loss	[2]	(15,182)	(3,458)	(29,326)	(8,293)
Equity in loss of Real Estate Ventures		$ (7,254)	$ (1,093)	$ (9,323)	$ (1,835)

[1] During the period ended September 30, 2016, Brandywine-AI Venture LLC recorded a property level impairment charge of $10.4 million. See additional details in the “Station Square Impairment” disclosure below.

[2] The nine-month period ended September 30, 2016 amount includes $7.1 million of acquisition deal costs related to the formation of the MAP Venture during the three-month period ended March 31, 2016.