Investments in Unconsolidated Joint Ventures - Schedules of Combined Financial Statements for the Unconsolidated Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Commercial real estate property, net	$ 7,906,006				$ 10,478,638				$ 7,906,006	$ 10,478,638
Cash and cash equivalents	127,888				279,443				127,888	279,443	$ 255,399	$ 281,409
Tenant and other receivables, related party receivables, and deferred rents receivable, net of allowance	57,644				53,772				57,644	53,772
Carrying Value	2,114,041				1,640,412				2,114,041	1,640,412
Other assets	310,688				614,067				310,688	614,067
Liabilities and members' equity
Mortgages and other loans payable, net	2,837,282				4,073,830				2,837,282	4,073,830
Deferred revenue	208,119				217,955				208,119	217,955
Other liabilities	188,005				206,238				188,005	206,238
Company's investments in unconsolidated joint ventures	2,362,989				1,890,186				2,362,989	1,890,186
Combined statements of income for the unconsolidated joint ventures
Ground rent									33,231	33,261	32,834
Real estate taxes									244,323	248,388	232,702
Interest expense, net of interest income									257,045	321,199	323,870
Amortization of deferred financing costs									16,498	24,564	27,348
Transaction related costs									(1,834)	7,528	11,430
Depreciation and amortization									403,320	821,041	560,887
Total expenses									1,346,445	1,868,599	1,585,568
Company's equity in net income from unconsolidated joint ventures	7,788	$ 4,078	$ 3,412	$ 6,614	(95)	$ (3,968)	$ 5,841	$ 10,096	21,892	11,874	13,028
Joint venture
Investment in Unconsolidated Joint Ventures
Management fees, base revenue									22,600	4,000	3,400
Assets
Commercial real estate property, net	12,822,133				9,131,717				12,822,133	9,131,717
Cash and cash equivalents	494,909				328,455				494,909	328,455
Tenant and other receivables, related party receivables, and deferred rents receivable, net of allowance	349,944				232,778				349,944	232,778
Carrying Value	202,539				336,164				202,539	336,164
Other assets	1,407,806				683,481				1,407,806	683,481
Total assets	15,277,331				10,712,595				15,277,331	10,712,595
Liabilities and members' equity
Mortgages and other loans payable, net	9,412,101				6,453,966				9,412,101	6,453,966
Deferred revenue	985,648				356,414				985,648	356,414
Other liabilities	411,053				391,500				411,053	391,500
Members' equity	4,468,529				3,510,715				4,468,529	3,510,715
Total liabilities and members' equity	$ 15,277,331				$ 10,712,595				15,277,331	10,712,595
Combined statements of income for the unconsolidated joint ventures
Total revenues									904,230	712,689	576,845
Operating expenses									157,610	126,913	106,613
Ground rent									16,794	14,924	14,083
Real estate taxes									142,774	111,673	89,734
Interest expense, net of interest income									250,063	197,741	199,126
Amortization of deferred financing costs									23,026	24,829	13,394
Transaction related costs									146	5,566	615
Depreciation and amortization									279,419	199,011	149,023
Total expenses									869,832	680,657	572,588
Loss on early extinguishment of debt									(7,899)	(1,606)	(1,089)
Net income before gain on sale									26,499	30,426	3,168
Company's equity in net income from unconsolidated joint ventures									$ 21,892	$ 11,874	$ 13,028