Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities:
Net (loss) income	$ (461,845)	$ 3,334,262	$ 422,603
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization (including amortization of deferred financing costs)	417,942	438,933	472,785
Net gains on disposition of wholly owned and partially owned assets	(381,320)	(845,499)	(246,031)
Equity in net loss (income) of partially owned entities	329,112	(78,865)	(9,149)
Real estate impairment losses and related write-offs	236,286	26,705	12,000
Net unrealized loss on real estate fund investments	226,107	106,109	84,706
Distributions of income from partially owned entities	175,246	116,826	78,831
Non-cash (gain on extinguishment of 608 Fifth Avenue lease liability) impairment loss on 608 Fifth Avenue right-of-use asset	(70,260)	75,220	0
Write-off of lease receivables deemed uncollectible	63,204	17,237	0
Stock-based compensation expense	48,677	53,908	31,722
Straight-lining of rents	24,404	9,679	(7,605)
Amortization of below-market leases, net	(16,878)	(19,830)	(38,573)
Credit losses on loans receivable	13,369	0	0
Decrease in fair value of marketable securities	4,938	5,533	26,453
Net gain on transfer to Fifth Avenue and Times Square JV	0	(2,571,099)	0
Prepayment penalty on redemption of senior unsecured notes due 2022	0	22,058	0
Purchase price fair value adjustment	0	0	(44,060)
Return of capital from real estate fund investments	0	0	20,290
Change in valuation of deferred tax assets and liabilities	0	0	12,835
Other non-cash adjustments	6,739	(3,472)	7,499
Changes in operating assets and liabilities:
Real estate fund investments	(7,197)	(10,000)	(68,950)
Tenant and other receivables, net	(5,330)	(25,988)	(14,532)
Prepaid assets	(137,452)	7,558	151,533
Other assets	(52,832)	(4,302)	(84,222)
Accounts payable and accrued expenses	14,868	5,940	5,869
Other liabilities	(3,538)	1,626	(11,363)
Net cash provided by operating activities	424,240	662,539	802,641
Cash Flows from Investing Activities:
Proceeds from sale of condominium units at 220 Central Park South	1,044,260	1,605,356	214,776
Development costs and construction in progress	(601,920)	(649,056)	(418,186)
Moynihan Train Hall expenditures	(395,051)	(438,935)	(74,609)
Additions to real estate	(155,738)	(233,666)	(234,602)
Proceeds from sales of marketable securities	28,375	168,314	4,101
Investments in partially owned entities	(8,959)	(18,257)	(37,131)
Distributions of capital from partially owned entities	2,389	24,880	100,178
Acquisitions of real estate and other	(1,156)	(69,699)	(574,812)
Proceeds from transfer of interest in Fifth Avenue and Times Square JV (net of $35,562 of transaction costs and $10,899 of deconsolidated cash and restricted cash)	0	1,248,743	0
Proceeds from redemption of 640 Fifth Avenue preferred equity	0	500,000	0
Proceeds from sale of real estate and related investments	0	324,201	219,731
Proceeds from repayments of loans receivable	0	1,395	25,757
Investments in loans receivable	0	0	(105,000)
Net consolidation of Farley Office and Retail Building	0	0	2,075
Net cash (used in) provided by investing activities	(87,800)	2,463,276	(877,722)
Cash Flows from Financing Activities:
Repayments of borrowings	(1,067,564)	(2,718,987)	(685,265)
Proceeds from borrowings	1,056,315	1,108,156	526,766
Dividends paid on common shares / Distributions to Vornado	(827,319)	(503,785)	(479,348)
Moynihan Train Hall reimbursement from Empire State Development	395,051	438,935	74,609
Proceeds from issuance of preferred shares	291,182	0	0
Contributions from noncontrolling interests / noncontrolling interests in consolidated subsidiaries	100,094	17,871	61,062
Distribution to noncontrolling interests / redeemable security holders and noncontrolling interests in consolidated subsidiaries	(91,514)	(80,194)	(76,149)
Dividends paid on preferred shares/ Distributions to preferred unitholders	(64,271)	(50,131)	(55,115)
Debt issuance costs	(10,901)	(15,588)	(12,908)
Proceeds received from exercise of employee share options (Vornado stock options) and other	5,862	6,903	7,309
Repurchase of shares (Class A units) related to stock compensation agreements and related tax withholdings and other	(137)	(8,692)	(12,969)
Purchase of marketable securities in connection with defeasance of mortgage payable	0	(407,126)	0
Prepayment penalty on redemption of senior unsecured notes due 2022	0	(22,058)	0
Redemption of preferred shares / units	0	(893)	(470,000)
Debt prepayment and extinguishment costs	0	0	(818)
Net cash used in financing activities	(213,202)	(2,235,589)	(1,122,826)
Net increase (decrease) in cash and cash equivalents and restricted cash	123,238	890,226	(1,197,907)
Cash and cash equivalents and restricted cash at beginning of period	1,607,131	716,905	1,914,812
Cash and cash equivalents and restricted cash at end of period	1,730,369	1,607,131	716,905
Reconciliation of Cash and Cash Equivalents and Restricted Cash:
Cash and cash equivalents at beginning of period	1,515,012	570,916	1,817,655
Restricted cash at beginning of period	92,119	145,989	97,157
Cash and cash equivalents and restricted cash at beginning of period	1,607,131	716,905	1,914,812
Cash and cash equivalents at end of period	1,624,482	1,515,012	570,916
Restricted cash at end of period	105,887	92,119	145,989
Cash and cash equivalents and restricted cash at end of period	1,730,369	1,607,131	716,905
Supplemental Disclosure of Cash Flow Information:
Cash payments for interest, excluding capitalized interest of $40,855, $67,980 and $67,402	210,052	283,613	311,835
Cash payments for income taxes	15,105	59,834	62,225
Non-Cash Investing and Financing Activities:
Reclassification of condominium units from "development costs and construction in progress" to "220 Central Park South condominium units ready for sale"	388,280	1,311,468	233,179
Redeemable Class A unit measurement adjustment	344,043	70,810	198,064
Write-off of fully depreciated assets	(189,250)	(122,813)	(86,064)
Accrued capital expenditures included in accounts payable and accrued expenses	117,641	109,975	88,115
Investments received in exchange for transfer to Fifth Avenue and Times Square JV:
Preferred equity	0	2,327,750	0
Common equity	0	1,449,495	0
Lease liabilities arising from the recognition of right-of-use assets	0	526,866	0
Marketable securities transferred in connection with the defeasance of mortgage payable	0	(407,126)	0
Special dividend/distribution declared and payable on January 15, 2020	0	398,292	0
Defeasance of mortgage payable	0	390,000	0
Recognition of negative basis related to the sale of our investment in 330 Madison Avenue	0	60,052	0
Amounts related to our investment in Pennsylvania Real Estate Investment Trust reclassified from "investments in partially owned entities" and "accumulated other comprehensive loss" to "marketable securities" upon conversion of operating partnership units to common shares	0	54,962	0
Vornado Realty L.P.
Cash Flows from Operating Activities:
Net (loss) income	(461,845)	3,334,262	422,603
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization (including amortization of deferred financing costs)	417,942	438,933	472,785
Net gains on disposition of wholly owned and partially owned assets	(381,320)	(845,499)	(246,031)
Equity in net loss (income) of partially owned entities	329,112	(78,865)	(9,149)
Real estate impairment losses and related write-offs	236,286	26,705	12,000
Net unrealized loss on real estate fund investments	226,107	106,109	84,706
Distributions of income from partially owned entities	175,246	116,826	78,831
Non-cash (gain on extinguishment of 608 Fifth Avenue lease liability) impairment loss on 608 Fifth Avenue right-of-use asset	(70,260)	75,220	0
Write-off of lease receivables deemed uncollectible	63,204	17,237	0
Stock-based compensation expense	48,677	53,908	31,722
Straight-lining of rents	24,404	9,679	(7,605)
Amortization of below-market leases, net	(16,878)	(19,830)	(38,573)
Credit losses on loans receivable	13,369	0	0
Decrease in fair value of marketable securities	4,938	5,533	26,453
Net gain on transfer to Fifth Avenue and Times Square JV	0	(2,571,099)	0
Prepayment penalty on redemption of senior unsecured notes due 2022	0	22,058	0
Purchase price fair value adjustment	0	0	(44,060)
Return of capital from real estate fund investments	0	0	20,290
Change in valuation of deferred tax assets and liabilities	0	0	12,835
Other non-cash adjustments	6,739	(3,472)	7,499
Changes in operating assets and liabilities:
Real estate fund investments	(7,197)	(10,000)	(68,950)
Tenant and other receivables, net	(5,330)	(25,988)	(14,532)
Prepaid assets	(137,452)	7,558	151,533
Other assets	(52,832)	(4,302)	(84,222)
Accounts payable and accrued expenses	14,868	5,940	5,869
Other liabilities	(3,538)	1,626	(11,363)
Net cash provided by operating activities	424,240	662,539	802,641
Cash Flows from Investing Activities:
Proceeds from sale of condominium units at 220 Central Park South	1,044,260	1,605,356	214,776
Development costs and construction in progress	(601,920)	(649,056)	(418,186)
Moynihan Train Hall expenditures	(395,051)	(438,935)	(74,609)
Additions to real estate	(155,738)	(233,666)	(234,602)
Proceeds from sales of marketable securities	28,375	168,314	4,101
Investments in partially owned entities	(8,959)	(18,257)	(37,131)
Distributions of capital from partially owned entities	2,389	24,880	100,178
Acquisitions of real estate and other	(1,156)	(69,699)	(574,812)
Proceeds from transfer of interest in Fifth Avenue and Times Square JV (net of $35,562 of transaction costs and $10,899 of deconsolidated cash and restricted cash)	0	1,248,743	0
Proceeds from redemption of 640 Fifth Avenue preferred equity	0	500,000	0
Proceeds from sale of real estate and related investments	0	324,201	219,731
Proceeds from repayments of loans receivable	0	1,395	25,757
Investments in loans receivable	0	0	(105,000)
Net consolidation of Farley Office and Retail Building	0	0	2,075
Net cash (used in) provided by investing activities	(87,800)	2,463,276	(877,722)
Cash Flows from Financing Activities:
Repayments of borrowings	(1,067,564)	(2,718,987)	(685,265)
Proceeds from borrowings	1,056,315	1,108,156	526,766
Dividends paid on common shares / Distributions to Vornado	(827,319)	(503,785)	(479,348)
Moynihan Train Hall reimbursement from Empire State Development	395,051	438,935	74,609
Proceeds from issuance of preferred shares	291,182	0	0
Contributions from noncontrolling interests / noncontrolling interests in consolidated subsidiaries	100,094	17,871	61,062
Distribution to noncontrolling interests / redeemable security holders and noncontrolling interests in consolidated subsidiaries	(91,514)	(80,194)	(76,149)
Dividends paid on preferred shares/ Distributions to preferred unitholders	(64,271)	(50,131)	(55,115)
Debt issuance costs	(10,901)	(15,588)	(12,908)
Proceeds received from exercise of employee share options (Vornado stock options) and other	5,862	6,903	7,309
Repurchase of shares (Class A units) related to stock compensation agreements and related tax withholdings and other	(137)	(8,692)	(12,969)
Purchase of marketable securities in connection with defeasance of mortgage payable	0	(407,126)	0
Prepayment penalty on redemption of senior unsecured notes due 2022	0	(22,058)	0
Redemption of preferred shares / units	0	(893)	(470,000)
Debt prepayment and extinguishment costs	0	0	(818)
Net cash used in financing activities	(213,202)	(2,235,589)	(1,122,826)
Net increase (decrease) in cash and cash equivalents and restricted cash	123,238	890,226	(1,197,907)
Cash and cash equivalents and restricted cash at beginning of period	1,607,131	716,905	1,914,812
Cash and cash equivalents and restricted cash at end of period	1,730,369	1,607,131	716,905
Reconciliation of Cash and Cash Equivalents and Restricted Cash:
Cash and cash equivalents at beginning of period	1,515,012	570,916	1,817,655
Cash and cash equivalents and restricted cash at beginning of period	1,607,131	716,905	1,914,812
Cash and cash equivalents at end of period	1,624,482	1,515,012	570,916
Cash and cash equivalents and restricted cash at end of period	1,730,369	1,607,131	716,905
Supplemental Disclosure of Cash Flow Information:
Cash payments for interest, excluding capitalized interest of $40,855, $67,980 and $67,402	210,052	283,613	311,835
Cash payments for income taxes	15,105	59,834	62,225
Non-Cash Investing and Financing Activities:
Reclassification of condominium units from "development costs and construction in progress" to "220 Central Park South condominium units ready for sale"	388,280	1,311,468	233,179
Redeemable Class A unit measurement adjustment	344,043	70,810	198,064
Write-off of fully depreciated assets	(189,250)	(122,813)	(86,064)
Accrued capital expenditures included in accounts payable and accrued expenses	117,641	109,975	88,115
Investments received in exchange for transfer to Fifth Avenue and Times Square JV:
Preferred equity	0	2,327,750	0
Common equity	0	1,449,495	0
Lease liabilities arising from the recognition of right-of-use assets	0	526,866	0
Marketable securities transferred in connection with the defeasance of mortgage payable	0	(407,126)	0
Special dividend/distribution declared and payable on January 15, 2020	0	398,292	0
Defeasance of mortgage payable	0	390,000	0
Recognition of negative basis related to the sale of our investment in 330 Madison Avenue	0	60,052	0
Amounts related to our investment in Pennsylvania Real Estate Investment Trust reclassified from "investments in partially owned entities" and "accumulated other comprehensive loss" to "marketable securities" upon conversion of operating partnership units to common shares	0	54,962	0
Farley Post Office Joint Venture
Increase (decrease) in assets and liabilities resulting from the consolidation or deconsolidation of Moynihan Train Hall and Farley Office and Retail Building:
Real estate, net, consolidated	0	0	401,708
Mortgage payable, net, consolidated	0	0	249,459
Farley Post Office Joint Venture | Vornado Realty L.P.
Increase (decrease) in assets and liabilities resulting from the consolidation or deconsolidation of Moynihan Train Hall and Farley Office and Retail Building:
Real estate, net, consolidated	0	0	401,708
Mortgage payable, net, consolidated	0	0	249,459
Moynihan Train Hall
Increase (decrease) in assets and liabilities resulting from the consolidation or deconsolidation of Moynihan Train Hall and Farley Office and Retail Building:
Real estate, net, deconsolidation	(1,291,804)	0	0
Financing obligation, deconsolidation	(1,291,804)	0	0
Real estate, net, consolidated	0	0	346,926
Financing obligation, consolidated	0	0	346,926
Moynihan Train Hall | Vornado Realty L.P.
Increase (decrease) in assets and liabilities resulting from the consolidation or deconsolidation of Moynihan Train Hall and Farley Office and Retail Building:
Real estate, net, deconsolidation	(1,291,804)	0	0
Financing obligation, deconsolidation	(1,291,804)	0	0
Real estate, net, consolidated	0	0	346,926
Financing obligation, consolidated	$ 0	$ 0	$ 346,926