Investment in Unconsolidated Real Estate Ventures - Summary of Results of Operations of Real Estate Ventures with Interests (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Equity Method Investments [Line Items]
Equity in loss of Real Estate Ventures		$ (11,503)	$ (811)	$ (790)
Unconsolidated Real Estate Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Revenue		214,452	164,928	147,236
Operating expenses		(110,265)	(70,136)	(61,268)
Provision for impairment	[1]	(10,476)	0	0
Interest expense, net		(43,283)	(34,584)	(36,511)
Depreciation and amortization		(85,738)	(68,100)	(57,109)
Net loss	[2]	(35,310)	(7,892)	(7,652)
Equity in loss of Real Estate Ventures		$ (11,503)	$ (811)	$ (790)

[1] During the year ended December 31, 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] During the year ended December 31, 2016, there were $7.1 million of acquisition deal costs related to the formation of the MAP Venture.