Segments - Schedule of NOI for Each Reportable Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Property-related revenues	$ 185,793	$ 180,806
Property-related operating expenses	(68,381)	(68,978)
NOI from unconsolidated joint ventures	5,411	4,740
NOI	122,823	116,568
New York [Member]
Segment Reporting Information [Line Items]
Property-related revenues	121,096	113,645
Property-related operating expenses	(48,103)	(47,161)
NOI from unconsolidated joint ventures	4,657	4,665
NOI	77,650	71,149
San Francisco [Member]
Segment Reporting Information [Line Items]
Property-related revenues	57,184	51,899
Property-related operating expenses	(16,346)	(14,116)
NOI from unconsolidated joint ventures	700
NOI	41,538	37,783
Washington, D.C. [Member]
Segment Reporting Information [Line Items]
Property-related revenues	7,403	15,449
Property-related operating expenses	(2,920)	(5,845)
NOI	4,483	9,604
Other [Member]
Segment Reporting Information [Line Items]
Property-related revenues	110	(187)
Property-related operating expenses	(1,012)	(1,856)
NOI from unconsolidated joint ventures	54	75
NOI	$ (848)	$ (1,968)