Segments - Schedule of Reconciliation of NOI to Net Income Attributable to Common Stockholders (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
NOI									$ 486,984,000	$ 448,262,000	$ 433,565,000
Fee income									18,629,000	24,212,000	16,931,000
Depreciation and amortization expense									(258,225,000)	(266,037,000)	(269,450,000)
General and administrative expenses									(57,563,000)	(61,577,000)	(53,510,000)
Transaction related costs									(1,471,000)	(2,027,000)	(2,404,000)
NOI from unconsolidated joint ventures									(20,730,000)	(19,643,000)	(17,195,000)
Income from unconsolidated joint ventures									3,468,000	20,185,000	7,413,000
Loss from unconsolidated real estate funds									(269,000)	(6,143,000)	(498,000)
Interest and other income (loss), net									8,117,000	(9,031,000)	6,934,000
Interest and debt expense									(147,653,000)	(143,762,000)	(153,138,000)
Loss on early extinguishment of debt										(7,877,000)	(4,608,000)
Real estate impairment loss									(46,000,000)
Gain on sale of real estate									36,845,000	133,989,000
Unrealized gain on interest rate swaps										1,802,000	39,814,000
Net income before income taxes									22,132,000	112,353,000	3,854,000
Income tax expense									(3,139,000)	(5,177,000)	(1,785,000)
Net income									18,993,000	107,176,000	2,069,000
Consolidated joint ventures									(8,182,000)	10,365,000	(15,423,000)
Consolidated real estate fund									(720,000)	(19,797,000)	1,316,000
Operating Partnership									(944,000)	(11,363,000)	2,104,000
Net income (loss) attributable to common stockholders	$ 5,318,000	$ 37,531,000	$ (34,816,000)	$ 1,114,000	$ (6,793,000)	$ (10,214,000)	$ 103,016,000	$ 372,000	$ 9,147,000	$ 86,381,000	$ (9,934,000)