Segments Disclosure - Schedule of NOI for Each Reportable Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Property-related revenues	$ 171,680	$ 169,501
Property-related operating expenses	(65,971)	(62,945)
NOI from unconsolidated joint ventures	4,823	4,428
NOI	110,532	110,984
New York [Member]
Segment Reporting Information [Line Items]
Property-related revenues	105,324	119,303
Property-related operating expenses	(44,759)	(44,137)
NOI from unconsolidated joint ventures	4,753	4,347
NOI	65,318	79,513
Washington, D.C. [Member]
Segment Reporting Information [Line Items]
Property-related revenues	23,787	19,982
Property-related operating expenses	(8,924)	(8,275)
NOI	14,863	11,707
San Francisco [Member]
Segment Reporting Information [Line Items]
Property-related revenues	41,939	29,619
Property-related operating expenses	(10,605)	(7,173)
NOI	31,334	22,446
Other [Member]
Segment Reporting Information [Line Items]
Property-related revenues	630	597
Property-related operating expenses	(1,683)	(3,360)
NOI from unconsolidated joint ventures	70	81
NOI	$ (983)	$ (2,682)