Schedule III - Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 1,399,923
Initial Cost
Land	1,332,556
Building & Improvements	4,894,397
Cost Capitalized Subsequent To Acquisition
Land	18,146
Building & Improvements	1,405,807
Gross Amount at Which Carried at Close of Period
Land	1,350,701
Building & Improvements (3)	6,300,206
Total	7,650,907	$ 7,355,079	$ 8,784,567	$ 8,513,935
Accumulated Depreciation	1,896,199	$ 1,956,077	$ 2,060,560	$ 2,099,137
420 Lexington Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	288,660
Initial Cost
Land	0
Building & Improvements	333,499
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	212,293
Gross Amount at Which Carried at Close of Period
Land	0
Building & Improvements (3)	545,792
Total	545,792
Accumulated Depreciation	183,070
711 Third Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	19,844
Building & Improvements	115,769
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	69,839
Gross Amount at Which Carried at Close of Period
Land	19,844
Building & Improvements (3)	185,608
Total	205,452
Accumulated Depreciation	71,105
555 W. 57th Street
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	18,846
Building & Improvements	140,946
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	2,376
Gross Amount at Which Carried at Close of Period
Land	18,846
Building & Improvements (3)	143,322
Total	162,168
Accumulated Depreciation	86,730
461 Fifth Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	0
Building & Improvements	88,276
Cost Capitalized Subsequent To Acquisition
Land	28,873
Building & Improvements	6,421
Gross Amount at Which Carried at Close of Period
Land	28,873
Building & Improvements (3)	94,697
Total	123,570
Accumulated Depreciation	38,024
750 Third Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	51,093
Building & Improvements	251,523
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	20,428
Gross Amount at Which Carried at Close of Period
Land	51,093
Building & Improvements (3)	271,951
Total	323,044
Accumulated Depreciation	114,853
625 Madison Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	0
Building & Improvements	291,319
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	62,282
Gross Amount at Which Carried at Close of Period
Land	0
Building & Improvements (3)	353,601
Total	353,601
Accumulated Depreciation	145,749
485 Lexington Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	450,000
Initial Cost
Land	78,282
Building & Improvements	452,631
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	(14,169)
Gross Amount at Which Carried at Close of Period
Land	78,282
Building & Improvements (3)	438,462
Total	516,744
Accumulated Depreciation	188,678
609 Fifth Avenue - Retail Condominium
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	52,882
Initial Cost
Land	16,869
Building & Improvements	107,185
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	62,554
Gross Amount at Which Carried at Close of Period
Land	16,869
Building & Improvements (3)	169,739
Total	186,608
Accumulated Depreciation	19,879
810 Seventh Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	114,077
Building & Improvements	550,819
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	5,205
Gross Amount at Which Carried at Close of Period
Land	114,077
Building & Improvements (3)	556,024
Total	670,101
Accumulated Depreciation	221,222
1185 Avenue of the Americas
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	0
Building & Improvements	791,106
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	127,030
Gross Amount at Which Carried at Close of Period
Land	0
Building & Improvements (3)	918,136
Total	918,136
Accumulated Depreciation	348,065
1350 Avenue of the Americas
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	90,941
Building & Improvements	431,517
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	0
Gross Amount at Which Carried at Close of Period
Land	90,941
Building & Improvements (3)	431,517
Total	522,458
Accumulated Depreciation	168,295
1-6 Landmark Square
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	100,000
Initial Cost
Land	27,852
Building & Improvements	161,343
Cost Capitalized Subsequent To Acquisition
Land	(6,939)
Building & Improvements	(33,873)
Gross Amount at Which Carried at Close of Period
Land	20,913
Building & Improvements (3)	127,470
Total	148,383
Accumulated Depreciation	36,923
7 Landmark Square
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	1,721
Building & Improvements	8,417
Cost Capitalized Subsequent To Acquisition
Land	(1,338)
Building & Improvements	(6,240)
Gross Amount at Which Carried at Close of Period
Land	383
Building & Improvements (3)	2,177
Total	2,560
Accumulated Depreciation	516
100 Church Street
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	200,212
Initial Cost
Land	34,994
Building & Improvements	183,932
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	6,326
Gross Amount at Which Carried at Close of Period
Land	34,994
Building & Improvements (3)	190,258
Total	225,252
Accumulated Depreciation	65,736
125 Park Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	120,900
Building & Improvements	270,598
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	15,899
Gross Amount at Which Carried at Close of Period
Land	120,900
Building & Improvements (3)	286,497
Total	407,397
Accumulated Depreciation	109,858
19 East 65th Street
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	8,603
Building & Improvements	2,074
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	0
Gross Amount at Which Carried at Close of Period
Land	8,603
Building & Improvements (3)	2,074
Total	10,677
Accumulated Depreciation	0
304 Park Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	54,489
Building & Improvements	90,643
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	5,139
Gross Amount at Which Carried at Close of Period
Land	54,489
Building & Improvements (3)	95,782
Total	150,271
Accumulated Depreciation	26,627
752-760 Madison Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	284,286
Building & Improvements	8,314
Cost Capitalized Subsequent To Acquisition
Land	(2,450)
Building & Improvements	63,077
Gross Amount at Which Carried at Close of Period
Land	281,836
Building & Improvements (3)	71,391
Total	353,227
Accumulated Depreciation	4,991
719 Seventh Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	50,000
Initial Cost
Land	41,180
Building & Improvements	46,232
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	(4,725)
Gross Amount at Which Carried at Close of Period
Land	41,180
Building & Improvements (3)	41,507
Total	82,687
Accumulated Depreciation	$ 3,356
719 Seventh Avenue | 719 Seventh Avenue
Gross Amount at Which Carried at Close of Period
Interest in property (as a percent)	75.00%
110 Greene Street
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 0
Initial Cost
Land	45,120
Building & Improvements	228,393
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	2,578
Gross Amount at Which Carried at Close of Period
Land	45,120
Building & Improvements (3)	230,971
Total	276,091
Accumulated Depreciation	42,909
185 Broadway
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	198,169
Initial Cost
Land	45,540
Building & Improvements	27,865
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	177,184
Gross Amount at Which Carried at Close of Period
Land	45,540
Building & Improvements (3)	205,049
Total	250,589
Accumulated Depreciation	419
885 Third Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	138,444
Building & Improvements	244,040
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	15,396
Gross Amount at Which Carried at Close of Period
Land	138,445
Building & Improvements (3)	259,438
Total	397,883
Accumulated Depreciation	7,885
690 Madison Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	60,000
Initial Cost
Land	13,820
Building & Improvements	51,732
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	0
Gross Amount at Which Carried at Close of Period
Land	13,820
Building & Improvements (3)	51,732
Total	65,552
Accumulated Depreciation	409
1591-1597 Broadway
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	123,919
Building & Improvements	0
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	0
Gross Amount at Which Carried at Close of Period
Land	123,919
Building & Improvements (3)	0
Total	123,919
Accumulated Depreciation	0
Other
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost
Land	1,734
Building & Improvements	16,224
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	610,787
Gross Amount at Which Carried at Close of Period
Land	1,734
Building & Improvements (3)	627,011
Total	628,745
Accumulated Depreciation	$ 10,900