Investments in Unconsolidated Joint Ventures - Schedules of Combined Financial Statements for the Unconsolidated Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Assets
Commercial real estate property, net	$ 7,333,209		$ 7,333,209		$ 6,414,798
Cash and cash equivalents	148,978	$ 287,240	148,978	$ 287,240	129,475
Tenant and other receivables, related party receivables, and deferred rents receivable	38,270		38,270		41,589
Other assets	235,355		235,355		295,679
Liabilities and equity
Mortgages and other loans payable, net	2,330,413		2,330,413		1,961,240
Deferred revenue/gain	122,941		122,941		94,453
Lease liabilities	387,602		387,602		3,603
Other liabilities	123,921		123,921		116,566
Company's investments in unconsolidated joint ventures	2,937,153		2,937,153		3,019,020
Combined statements of income for the unconsolidated joint ventures
Operating expenses	58,317	56,237	116,015	116,019
Real estate taxes	46,694	45,322	93,382	90,983
Interest expense, net of interest income	47,160	53,611	97,685	101,527
Amortization of deferred financing costs	2,712	3,546	5,454	7,083
Transaction related costs	261	348	316	510
Depreciation and amortization	69,461	67,914	137,804	137,302
Total expenses	258,383	258,303	518,711	516,585
Company's equity in net (loss) income from unconsolidated joint ventures	(7,546)	4,702	(12,780)	8,738
Joint venture
Assets
Commercial real estate property, net	14,151,061		14,151,061		14,347,673
Cash and cash equivalents	319,429		319,429		381,301
Tenant and other receivables, related party receivables, and deferred rents receivable	321,603		321,603		273,141
Debt and preferred equity investments, net	0		0		44,357
Other assets	2,093,491		2,093,491		2,187,166
Total assets	16,885,584		16,885,584		17,233,638
Liabilities and equity
Mortgages and other loans payable, net	8,591,391		8,591,391		8,950,622
Deferred revenue/gain	1,558,660		1,558,660		1,660,838
Lease liabilities	900,601		900,601		637,168
Other liabilities	290,007		290,007		309,145
Equity	5,544,925		5,544,925		5,675,865
Total liabilities and equity	16,885,584		16,885,584		17,233,638
Company's investments in unconsolidated joint ventures	2,937,153		2,937,153		$ 3,019,020
Combined statements of income for the unconsolidated joint ventures
Total revenues	290,448	314,195	597,967	635,136
Operating expenses	48,514	50,356	102,638	110,129
Operating lease rent	6,234	4,457	12,135	8,850
Real estate taxes	51,987	55,838	106,223	112,865
Interest expense, net of interest income	93,693	91,648	190,316	181,389
Amortization of deferred financing costs	4,782	7,350	9,998	12,466
Depreciation and amortization	103,681	111,495	208,012	216,575
Total expenses	308,891	321,144	629,322	642,274
Net loss before gain on sale	(18,443)	(6,949)	(31,355)	(7,138)
Company's equity in net (loss) income from unconsolidated joint ventures	(7,546)	4,702	(12,780)	8,738
Management Service, Base | Joint venture
Investment in Unconsolidated Joint Ventures
Escalation and reimbursement	$ 3,900	$ 3,000	$ 6,400	$ 6,900