Segments Disclosure - Schedule of Reconciliation of NOI to Net Loss Attributable to Common Stockholders (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting [Abstract]
NOI	$ 110,984	$ 101,588
Fee income	3,417	1,535
Depreciation and amortization expense	(74,812)	(73,583)
General and administrative expenses	(13,961)	(12,613)
Acquisition and transaction related costs	(935)	(1,139)
NOI from unconsolidated joint ventures and funds	(4,428)	(3,781)
Income from unconsolidated joint ventures	1,496	975
Income from real estate fund investments		5,221
Loss from unconsolidated real estate funds	(326)
Interest and investment income, net	1,700	854
Interest and debt expense	(37,119)	(41,888)
Unrealized gain on interest rate swaps	6,860	11,978
Net loss before income taxes	(7,124)	(10,853)
Income tax expense	(363)	(574)
Net loss	(7,487)	(11,427)
Consolidated real estate funds	674	(2,209)
Consolidated joint ventures	(1,252)	1,541
Operating Partnership	1,571	2,364
Net loss attributable to common stockholders	$ (6,494)	$ (9,731)