Investments in Unconsolidated Joint Ventures - Summary of Financial Information for Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Net Investment in Properties	$ 20,582,954				$ 14,230,575				$ 20,582,954	$ 14,230,575
Total Assets	36,076,291				23,068,131				36,076,291	23,068,131
Mortgage Loans	239,222				104,934				239,222	104,934
Liabilities	17,587,944				12,418,566				17,587,944	12,418,566
Equity / (Deficit)	17,717,697				9,879,312				17,717,697	9,879,312
Investments in unconsolidated joint ventures	1,148,158				1,287,109				1,148,158	1,287,109
Revenues	1,062,609	$ 1,024,668	$ 992,995	$ 823,337	787,463	$ 806,466	$ 800,797	$ 814,515	3,903,609	3,209,241	$ 3,046,478
Net income	59,508	$ (1,454)	$ 75,978	$ 228,698	349,326	$ 67,574	$ 61,324	$ 120,997	362,730	599,221	341,115
Equity in (loss) earnings of unconsolidated joint ventures									(57,629)	8,067	32,979
Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures	1,148,158				1,287,109				1,148,158	1,287,109	175,108
Equity in (loss) earnings of unconsolidated joint ventures									(57,629)	8,067	32,979
Corporate Joint Venture | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Net Investment in Properties	2,723,496				2,627,689				2,723,496	2,627,689	1,070,661
Total Assets	4,602,938				4,877,750				4,602,938	4,877,750	1,371,431
Mortgage Loans	1,316,350				1,360,384				1,316,350	1,360,384	728,338
Liabilities	1,660,303				1,680,946				1,660,303	1,680,946	876,157
Equity / (Deficit)	$ 2,942,635				$ 3,196,804				2,942,635	3,196,804	495,274
Revenues									535,241	379,600	214,815
Property Operating Expense									(208,587)	(143,143)	(75,826)
Net Operating Income									326,654	236,457	138,989
Net income									$ (135,097)	$ 8,357	$ 47,222
2001 Sixth Avenue | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures					50.00%					50.00%	50.00%
Net Investment in Properties					$ 30,748					$ 30,748	$ 32,786
Total Assets					47,485					47,485	49,278
Mortgage Loans					134,583					134,583	134,527
Liabilities					140,354					140,354	139,569
Equity / (Deficit)					$ (92,869)					(92,869)	(90,291)
Revenues										56,266	52,806
Property Operating Expense										(19,254)	(17,264)
Net Operating Income										37,012	35,542
Net income										$ 27,422	$ 25,612
2020 Fifth Avenue | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures	50.00%				50.00%				50.00%	50.00%	50.00%
Net Investment in Properties	$ 43,255				$ 43,918				$ 43,255	$ 43,918	$ 44,644
Total Assets	52,435				54,325				52,435	54,325	54,855
Mortgage Loans	47,748				48,000				47,748	48,000	48,000
Liabilities	48,119				48,703				48,119	48,703	48,333
Equity / (Deficit)	$ 4,316				$ 5,622				4,316	5,622	6,522
Revenues									10,107	9,868	9,417
Property Operating Expense									(2,887)	(2,544)	(2,156)
Net Operating Income									7,220	7,324	7,261
Net income									$ 4,393	$ 4,649	$ 4,689
CenturyLink | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures	50.00%				50.00%				50.00%	50.00%	50.00%
Net Investment in Properties	$ 142,596				$ 148,941				$ 142,596	$ 148,941	$ 151,256
Total Assets	181,464				187,241				181,464	187,241	201,527
Liabilities	8,264				9,947				8,264	9,947	9,337
Equity / (Deficit)	$ 173,200				$ 177,294				173,200	177,294	192,190
Revenues									25,006	24,680	21,394
Property Operating Expense									(10,241)	(9,251)	(7,164)
Net Operating Income									14,765	15,429	14,230
Net income									$ 5,581	$ 6,712	$ 6,958
Mitsubishi | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures	50.00%				50.00%				50.00%	50.00%	50.00%
Net Investment in Properties	$ 734,362				$ 554,828				$ 734,362	$ 554,828	$ 332,373
Total Assets	968,957				753,743				968,957	753,743	469,159
Mortgage Loans	243,911				231,046				243,911	231,046	228,075
Liabilities	358,749				303,130				358,749	303,130	285,424
Equity / (Deficit)	$ 610,208				450,613				610,208	450,613	183,735
Revenues									154,114	84,344	59,300
Property Operating Expense									(71,001)	(39,300)	(26,360)
Net Operating Income									83,113	45,044	32,940
Net income									$ 43,746	18,751	$ 15,884
Ascenty Acquisition
Schedule of Equity Method Investments [Line Items]
Mortgage Loans					$ 571,873					$ 571,873
Ascenty Acquisition | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures	51.00%				51.00%				51.00%	51.00%
Net Investment in Properties	$ 594,322				$ 548,114				$ 594,322	$ 548,114
Total Assets	1,862,402				2,178,663				1,862,402	2,178,663
Mortgage Loans	720,623				629,500				720,623	629,500
Liabilities	833,801				764,603				833,801	764,603
Equity / (Deficit)	$ 1,028,601				$ 1,414,060				1,028,601	1,414,060
Revenues									165,680	112,052
Property Operating Expense									(60,640)	(40,250)
Net Operating Income									105,040	71,802
Net income									$ (191,161)	$ (54,606)
Mapletree JV | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures	20.00%				20.00%				20.00%	20.00%
Net Investment in Properties	$ 723,678				$ 765,443				$ 723,678	$ 765,443
Total Assets	985,900				1,042,661				985,900	1,042,661
Liabilities	38,140				23,796				38,140	23,796
Equity / (Deficit)	$ 947,760				$ 1,018,865				947,760	1,018,865
Revenues									106,966	17,852
Property Operating Expense									(40,904)	(6,774)
Net Operating Income									66,062	11,078
Net income									$ (11,473)	$ (1,872)
PREI | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures	20.00%				20.00%				20.00%	20.00%	20.00%
Net Investment in Properties	$ 359,706				$ 365,993				$ 359,706	$ 365,993	$ 375,016
Total Assets	409,836				421,635				409,836	421,635	433,024
Mortgage Loans	211,205				210,915				211,205	210,915	210,626
Liabilities	278,645				281,344				278,645	281,344	283,899
Equity / (Deficit)	$ 131,191				$ 140,291				131,191	140,291	149,125
Revenues									41,459	42,157	42,058
Property Operating Expense									(9,182)	(9,918)	(8,457)
Net Operating Income									32,277	32,239	33,601
Net income									$ 9,446	$ 9,968	$ (4,159)
GCEAR | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures	20.00%				20.00%				20.00%	20.00%	20.00%
Net Investment in Properties	$ 106,316				$ 109,803				$ 106,316	$ 109,803	$ 111,909
Total Assets	117,573				127,444				117,573	127,444	139,268
Mortgage Loans	89,300				101,902				89,300	101,902	101,885
Liabilities	90,709				104,363				90,709	104,363	104,268
Equity / (Deficit)	26,864				23,081				26,864	23,081	35,000
Revenues									21,401	21,120	20,457
Property Operating Expense									(6,787)	(9,073)	(8,546)
Net Operating Income									14,614	12,047	11,911
Net income									4,642	(2,636)	$ (2,177)
Other | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures											17.00%
Net Investment in Properties	19,261				59,901				19,261	59,901	$ 22,677
Total Assets	24,371				64,553				24,371	64,553	24,320
Mortgage Loans	3,563				4,438				3,563	4,438	5,225
Liabilities	3,876				4,706				3,876	4,706	5,327
Equity / (Deficit)	$ 20,495				$ 59,847				20,495	59,847	18,993
Revenues									10,508	11,261	9,383
Property Operating Expense									(6,945)	(6,779)	(5,879)
Net Operating Income									3,563	4,482	3,504
Net income									$ (271)	$ (31)	$ 415
Minimum | Other | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures					7.00%					7.00%
Maximum | Other | Unconsolidated Joint Ventures.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in joint ventures					17.00%					17.00%