SL Green Realty (SLG) 10-Q 10 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	May 07, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	1-13199
Entity Registrant Name	SL GREEN REALTY CORP
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	13-3956775
Entity Address, Address Line One	One Vanderbilt Avenue
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10017
City Area Code	212
Local Phone Number	594-2700
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		69,353,968
Entity Central Index Key	0001040971
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false
Former Address
Document Information [Line Items]
Entity Address, Address Line One	420 Lexington Avenue
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10170
Common Stock
Document Information [Line Items]
Trading Symbol	SLG
Title of 12(b) Security	Common Stock, $0.01 par value
Security Exchange Name	NYSE
Preferred Stock
Document Information [Line Items]
Trading Symbol	SLG.PRI
Title of 12(b) Security	6.500% Series I Cumulative Redeemable Preferred Stock, $0.01 par value
Security Exchange Name	NYSE
SL Green Operating Partnership
Document Information [Line Items]
Entity File Number	33-167793-02
Entity Registrant Name	SL GREEN OPERATING PARTNERSHIP, L.P.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-3960938
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		1,025,366
Entity Central Index Key	0001492869
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Commercial real estate properties, at cost:
Land and land interests		$ 1,445,199	$ 1,315,832
Building and improvements		4,096,930	4,168,193
Building leasehold and improvements		1,730,418	1,448,134
Right of use asset - financing leases		55,711	55,711
Right of use asset - operating leases		502,316	367,209
Total commercial real estate properties, at cost		7,830,574	7,355,079
Less: accumulated depreciation		(2,004,945)	(1,956,077)
Total commercial real estate properties, net		5,825,629	5,399,002
Cash and cash equivalents		304,999	266,059
Restricted cash		96,608	106,736
Investments in marketable securities		23,784	28,570
Tenant and other receivables		42,505	44,507
Related party receivables		34,310	34,657
Deferred rents receivable		304,420	302,791
Debt and preferred equity investments, net of discounts and deferred origination fees of $9,817 and $11,232 and allowances of $13,213 and $13,213 in 2021 and 2020, respectively		1,097,202	1,076,542
Investments in unconsolidated joint ventures		3,698,701	3,823,322
Deferred costs, net		170,252	177,168
Other assets		445,635	448,213
Total assets	[1]	12,044,045	11,707,567
Liabilities
Mortgages and other loans payable, net		1,848,701	1,979,972
Revolving credit facility, net		625,809	105,262
Unsecured term loans, net		1,495,620	1,495,275
Unsecured notes, net		1,248,622	1,248,219
Accrued interest payable		22,796	14,825
Other liabilities		267,908	302,798
Accounts payable and accrued expenses		120,015	151,309
Deferred revenue		119,215	118,572
Lease liability - financing leases		152,622	152,521
Lease liability - operating leases		455,385	339,458
Dividend and distributions payable		24,924	149,294
Security deposits		54,181	53,836
Junior subordinated deferrable interest debentures held by trusts that issued trust preferred securities		100,000	100,000
Total liabilities	[1]	6,535,798	6,211,341
Commitments and contingencies
Noncontrolling interests in Operating Partnership		374,124	358,262
Preferred units		198,503	202,169
Equity
Series I Preferred Stock, $0.01 par value, $25.00 liquidation preference, 9,200 issued and outstanding at both March 31, 2021 and December 31, 2020		221,932	221,932
Common stock, $0.01 par value, 160,000 shares authorized and 70,380 and 69,534 issued and outstanding at March 31, 2021 and December 31, 2020, respectively (including 1,026 and 1,026 shares held in treasury at March 31, 2021 and December 31, 2020, respectively)		705	716
Additional paid-in-capital		3,913,258	3,862,949
Treasury stock at cost		(124,049)	(124,049)
Accumulated other comprehensive loss		(18,897)	(67,247)
Retained earnings		918,077	1,015,462
Total SL Green stockholders' equity		4,911,026	4,909,763
Noncontrolling interests in other partnerships		24,594	26,032
Total equity		4,935,620	4,935,795
SL Green stockholders equity:
Total liabilities and equity/capital		12,044,045	11,707,567
SL Green Operating Partnership
Commercial real estate properties, at cost:
Land and land interests		1,445,199	1,315,832
Building and improvements		4,096,930	4,168,193
Building leasehold and improvements		1,730,418	1,448,134
Right of use asset - financing leases		55,711	55,711
Right of use asset - operating leases		502,316	367,209
Total commercial real estate properties, at cost		7,830,574	7,355,079
Less: accumulated depreciation		(2,004,945)	(1,956,077)
Total commercial real estate properties, net		5,825,629	5,399,002
Cash and cash equivalents		304,999	266,059
Restricted cash		96,608	106,736
Investments in marketable securities		23,784	28,570
Tenant and other receivables		42,505	44,507
Related party receivables		34,310	34,657
Deferred rents receivable		304,420	302,791
Debt and preferred equity investments, net of discounts and deferred origination fees of $9,817 and $11,232 and allowances of $13,213 and $13,213 in 2021 and 2020, respectively		1,097,202	1,076,542
Investments in unconsolidated joint ventures		3,698,701	3,823,322
Deferred costs, net		170,252	177,168
Other assets		445,635	448,213
Total assets	[2]	12,044,045	11,707,567
Liabilities
Mortgages and other loans payable, net		1,848,701	1,979,972
Revolving credit facility, net		625,809	105,262
Unsecured term loans, net		1,495,620	1,495,275
Unsecured notes, net		1,248,622	1,248,219
Accrued interest payable		22,796	14,825
Other liabilities		267,908	302,798
Accounts payable and accrued expenses		120,015	151,309
Deferred revenue		119,215	118,572
Lease liability - financing leases		152,622	152,521
Lease liability - operating leases		455,385	339,458
Dividend and distributions payable		24,924	149,294
Security deposits		54,181	53,836
Liabilities related to assets held for sale		0	0
Junior subordinated deferrable interest debentures held by trusts that issued trust preferred securities		100,000	100,000
Total liabilities	[2]	6,535,798	6,211,341
Commitments and contingencies
Limited partner interests in SLGOP (4,156 and 3,939 limited partner common units outstanding at March 31, 2021 and December 31, 2020, respectively)		374,124	358,262
Preferred units		198,503	202,169
Equity
Accumulated other comprehensive loss		(18,897)	(67,247)
SL Green stockholders equity:
Series I Preferred Units, $25.00 liquidation preference, 9,200 issued and outstanding at both March 31, 2021 and December 31, 2020		221,932	221,932
SL Green partners' capital (735 and 724 general partner common units and 68,619 and 67,784 limited partner common units outstanding at March 31, 2021 and December 31, 2020, respectively)		4,707,991	4,755,078
Total SLGOP partners' capital		4,911,026	4,909,763
Noncontrolling interests in other partnerships		24,594	26,032
Total capital		4,935,620	4,935,795
Total liabilities and equity/capital		12,044,045	11,707,567
Variable Interest Entity, Primary Beneficiary
Commercial real estate properties, at cost:
Land and land interests		179,600	41,200
Building and improvements		282,300	57,900
Building leasehold and improvements		2,000	2,000
Right of use asset - financing leases		53,200	37,800
Less: accumulated depreciation		(16,400)	(10,300)
Other assets		297,100	289,500
Liabilities
Mortgages and other loans payable, net		368,600	94,000
Accrued interest payable		900	700
Other liabilities		31,200	56,600
Lease liability - financing leases		$ 45,300	$ 29,900
[1]	The Company's consolidated balance sheets include assets and liabilities of consolidated variable interest entities ("VIEs"). See Note 2. The consolidated balance sheets include the following amounts related to our consolidated VIEs, excluding the Operating Partnership: $179.6 million and $41.2 million of land, $282.3 million and $57.9 million of building and improvements, $2.0 million and $2.0 million of building and leasehold improvements, $53.2 million and $37.8 million of right of use assets, $16.4 million and $10.3 million of accumulated depreciation, $297.1 million and $289.5 million of other assets included in other line items, $368.6 million and $94.0 million of real estate debt, net, $0.9 million and $0.7 million of accrued interest payable, $45.3 million and $29.9 million of lease liabilities, and $31.2 million and $56.6 million of other liabilities included in other line items as of March 31, 2021 and December 31, 2020, respectively.
[2]	The Operating Partnership's consolidated balance sheets include assets and liabilities of consolidated variable interest entities ("VIEs"). See Note 2. The consolidated balance sheets include the following amounts related to our consolidated VIEs, excluding the Operating Partnership: $179.6 million and $41.2 million of land, $282.3 million and $57.9 million of building and improvements, $2.0 million and $2.0 million of building and leasehold improvements, $53.2 million and $37.8 million of right of use assets, $16.4 million and $10.3 million of accumulated depreciation, $297.1 million and $289.5 million of other assets included in other line items, $368.6 million and $94.0 million of real estate debt, net, $0.9 million and $0.7 million of accrued interest payable, $45.3 million and $29.9 million of lease liabilities, and $31.2 million and $56.6 million of other liabilities included in other line items as of March 31, 2021 and December 31, 2020, respectively.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt and preferred equity investments, discount and deferred origination fees	$ 9,817	$ 11,232
Allowance for loan and lease losses, real estate	$ 13,213	$ 13,213
Preferred stock, par value (in dollars per share)	$ 0.01
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	160,000,000	160,000,000
Common stock, shares issued (in shares)	70,380,000	69,534,000
Common stock, shares outstanding (in shares)	70,380,000	69,534,000
Treasury stock, shares (in shares)	1,026,000	1,026,000
Land and land interests	$ 1,445,199	$ 1,315,832
Building and improvements	4,096,930	4,168,193
Building leasehold and improvements	1,730,418	1,448,134
Right of use asset - financing leases	55,711	55,711
Accumulated depreciation	2,004,945	1,956,077
Other assets	445,635	448,213
Mortgages and other loans payable, net	1,848,701	1,979,972
Accrued interest payable	22,796	14,825
Lease liability - financing leases	152,622	152,521
Other liabilities	$ 267,908	$ 302,798
Series I Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference (in dollars per share)	$ 25	$ 25
Preferred stock, shares issued (in shares)	9,200,000	9,200,000
Preferred stock, shares outstanding (in shares)	9,200,000	9,200,000
SL Green Operating Partnership
Debt and preferred equity investments, discount and deferred origination fees	$ 9,817	$ 11,232
Allowance for loan and lease losses, real estate	$ 13,213	$ 13,213
Limited partner interests in Operating Partnership, limited partner common units outstanding (shares)	4,156,000	3,939,000
SL Green partner's capital, general partner common units outstanding (shares)	735,000	724,000
SL Green partners' capital, limited partner common units outstanding (shares)	68,619,000	67,784,000
Land and land interests	$ 1,445,199	$ 1,315,832
Building and improvements	4,096,930	4,168,193
Building leasehold and improvements	1,730,418	1,448,134
Right of use asset - financing leases	55,711	55,711
Accumulated depreciation	2,004,945	1,956,077
Other assets	445,635	448,213
Mortgages and other loans payable, net	1,848,701	1,979,972
Accrued interest payable	22,796	14,825
Lease liability - financing leases	152,622	152,521
Other liabilities	$ 267,908	$ 302,798
SL Green Operating Partnership | Series I Preferred Stock
Preferred units, liquidation preference (in dollars per share)	$ 25	$ 25
Preferred units, shares issued (in shares)	9,200,000	9,200,000
Preferred units, shares outstanding (in shares)	9,200,000	9,200,000
Variable Interest Entity, Primary Beneficiary
Land and land interests	$ 179,600	$ 41,200
Building and improvements	282,300	57,900
Building leasehold and improvements	2,000	2,000
Right of use asset - financing leases	53,200	37,800
Accumulated depreciation	16,400	10,300
Other assets	297,100	289,500
Mortgages and other loans payable, net	368,600	94,000
Accrued interest payable	900	700
Lease liability - financing leases	45,300	29,900
Other liabilities	$ 31,200	$ 56,600

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues
Rental revenue, net	$ 188,089	$ 222,631
Investment income	19,273	38,533
Other income	18,740	53,139
Total revenues	226,102	314,303
Expenses
Operating expenses, including related party expenses of $2,225 in 2021 and $3,749 in 2020	42,284	53,866
Real estate taxes	45,411	46,622
Operating lease rent	6,739	7,367
Interest expense, net of interest income	23,388	37,494
Amortization of deferred financing costs	3,774	2,500
Depreciation and amortization	62,996	68,279
Loan loss and other investment reserves, net of recoveries	0	11,248
Transaction related costs	22	65
Marketing, general and administrative	22,885	19,570
Total expenses	207,499	247,011
Equity in net loss from unconsolidated joint ventures	(2,864)	(12,814)
Equity in net loss on sale of interest in unconsolidated joint venture/real estate	(12,629)	0
Purchase price and other fair value adjustments	2,664	0
(Loss) gain on sale of real estate, net	(1,388)	72,636
Depreciable real estate reserves and impairment	(8,241)	0
Net (loss) income	(3,855)	127,114
Net loss (income) attributable to noncontrolling interests:
Noncontrolling interests in the Operating Partnership	476	(6,202)
Noncontrolling interests in other partnerships	1,499	293
Preferred units distributions	(1,846)	(2,666)
Net income (loss) attributable to SL Green/SLGOP	(3,726)	118,539
Perpetual preferred stock dividends	(3,738)	(3,738)
Net income attributable to SL Green common stockholders	$ (7,464)	$ 114,801
Basic earnings per share (usd per share)	$ (0.11)	$ 1.51
Diluted earnings per share (usd per share)	$ (0.11)	$ 1.51
Basic weighted average common shares outstanding (in shares)	69,010	75,656
Diluted weighted average common shares and common share equivalents outstanding (in shares)	74,070	80,352
SL Green Operating Partnership
Revenues
Rental revenue, net	$ 188,089	$ 222,631
Investment income	19,273	38,533
Other income	18,740	53,139
Total revenues	226,102	314,303
Expenses
Operating expenses, including related party expenses of $2,225 in 2021 and $3,749 in 2020	42,284	53,866
Real estate taxes	45,411	46,622
Operating lease rent	6,739	7,367
Interest expense, net of interest income	23,388	37,494
Amortization of deferred financing costs	3,774	2,500
Depreciation and amortization	62,996	68,279
Loan loss and other investment reserves, net of recoveries	0	11,248
Transaction related costs	22	65
Marketing, general and administrative	22,885	19,570
Total expenses	207,499	247,011
Equity in net loss from unconsolidated joint ventures	(2,864)	(12,814)
Equity in net loss on sale of interest in unconsolidated joint venture/real estate	(12,629)	0
Purchase price and other fair value adjustments	2,664	0
(Loss) gain on sale of real estate, net	(1,388)	72,636
Depreciable real estate reserves and impairment	(8,241)	0
Net (loss) income	(3,855)	127,114
Net loss (income) attributable to noncontrolling interests:
Noncontrolling interests in other partnerships	1,499	293
Preferred units distributions	(1,846)	(2,666)
Net income (loss) attributable to SL Green/SLGOP	(4,202)	124,741
Perpetual preferred unit distributions	(3,738)	(3,738)
Net (loss) income attributable to SLGOP common unitholders	$ (7,940)	$ 121,003
Basic earnings per unit (usd per share)	$ (0.11)	$ 1.51
Diluted earnings per unit (usd per share)	$ (0.11)	$ 1.51
Basic weighted average common units outstanding (in shares)	73,158	79,876
Diluted weighted average common units and common unit equivalents outstanding (in shares)	74,070	80,352

Consolidated Statements of Op_2

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating expenses, paid to related parties	$ 2,225	$ 3,749
SL Green Operating Partnership
Operating expenses, paid to related parties	$ 2,225	$ 3,749

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net (loss) income	$ (3,855)	$ 127,114
Other comprehensive income (loss):
Increase (decrease) in unrealized value of derivative instruments, including SL Green's share of joint venture derivative instruments	51,263	(50,735)
Decrease in unrealized value of marketable securities	(258)	(4,534)
Other comprehensive income (loss)	51,005	(55,269)
Comprehensive income	47,150	71,845
Net loss (income) attributable to noncontrolling interests and preferred units distributions	129	(8,575)
Net loss attributable to noncontrolling interests	1,499	293
Other comprehensive (income) loss attributable to noncontrolling interests	(2,655)	2,886
Comprehensive income attributable to SL Green/SLGOP	44,624	66,156
SL Green Operating Partnership
Net (loss) income	(3,855)	127,114
Other comprehensive income (loss):
Increase (decrease) in unrealized value of derivative instruments, including SL Green's share of joint venture derivative instruments	51,263	(50,735)
Decrease in unrealized value of marketable securities	(258)	(4,534)
Other comprehensive income (loss)	51,005	(55,269)
Comprehensive income	47,150	71,845
Net loss attributable to noncontrolling interests	1,499	293
Other comprehensive (income) loss attributable to noncontrolling interests	(2,655)	2,886
Comprehensive income attributable to SL Green/SLGOP	$ 45,994	$ 75,024

Consolidated Statement of Equit

Consolidated Statement of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In-Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Retained Earnings	Noncontrolling Interests	Series I Preferred StockPreferred Stock	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, AdjustmentRetained Earnings	Cumulative Effect, Period of Adoption, Adjusted Balance	Cumulative Effect, Period of Adoption, Adjusted BalanceCommon Stock	Cumulative Effect, Period of Adoption, Adjusted BalanceAdditional Paid-In-Capital	Cumulative Effect, Period of Adoption, Adjusted BalanceTreasury Stock	Cumulative Effect, Period of Adoption, Adjusted BalanceAccumulated Other Comprehensive Loss	Cumulative Effect, Period of Adoption, Adjusted BalanceRetained Earnings	Cumulative Effect, Period of Adoption, Adjusted BalanceNoncontrolling Interests	Cumulative Effect, Period of Adoption, Adjusted BalanceSeries I Preferred StockPreferred Stock
Beginning Balance at Dec. 31, 2019	$ 5,517,198	$ 803	$ 4,286,395	$ (124,049)	$ (28,485)	$ 1,084,719	$ 75,883	$ 221,932	$ (39,184)	$ (39,184)	$ 5,478,014	$ 803	$ 4,286,395	$ (124,049)	$ (28,485)	$ 1,045,535	$ 75,883	$ 221,932
Beginning Balance (in shares) at Dec. 31, 2019		76,956										76,956
Increase (Decrease) in Stockholders' Equity
Accounting Standards Update	us-gaap:AccountingStandardsUpdate201613Member
Net loss	$ 118,246					118,539	(293)
Acquisition of subsidiary interest from noncontrolling interest	(1,536)		(3,123)				1,587
Other comprehensive income	(52,383)				(52,383)
Preferred dividends	(3,738)					(3,738)
DRSPP proceeds (in shares)		2
DRSPP proceeds	166		166
Conversion of units of the Operating Partnership to common stock (in shares)		1
Conversion of units in the Operating Partnership for common stock	84		84
Reallocation of noncontrolling interest in the Operating Partnership	38,529					38,529
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in shares)		(32)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	5,502	$ (1)	5,503
Repurchases of common stock (in shares)		(2,562)
Repurchases of common stock	(219,576)	$ (26)	(142,719)			(76,831)
Contributions to consolidated joint venture interests	3,814						3,814
Cash distributions to noncontrolling interests	(492)						(492)
Cash distributions declared (per common share, none of which represented a return of capital for federal income tax purposes)	(22,665)					(22,665)
Ending Balance at Mar. 31, 2020	5,343,965	$ 776	4,146,306	(124,049)	(80,868)	1,099,369	80,499	221,932
Ending Balance (in shares) at Mar. 31, 2020		74,365
Beginning Balance at Dec. 31, 2019	5,517,198	$ 803	4,286,395	(124,049)	(28,485)	1,084,719	75,883	221,932	$ (39,184)	$ (39,184)	$ 5,478,014	$ 803	$ 4,286,395	$ (124,049)	$ (28,485)	$ 1,045,535	$ 75,883	$ 221,932
Beginning Balance (in shares) at Dec. 31, 2019		76,956										76,956
Ending Balance at Dec. 31, 2020	4,935,795	$ 716	3,862,949	(124,049)	(67,247)	1,015,462	26,032	221,932
Ending Balance (in shares) at Dec. 31, 2020		68,508
Increase (Decrease) in Stockholders' Equity
Net loss	(5,225)					(3,726)	(1,499)
Other comprehensive income	48,350				48,350
Preferred dividends	(3,738)					(3,738)
DRSPP proceeds (in shares)		5
DRSPP proceeds	351		351
Reallocation of noncontrolling interest in the Operating Partnership	(26,609)					(26,609)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in shares)		113
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	6,728	$ 2	6,726
Repurchases of common stock (in shares)		(1,306)
Repurchases of common stock	(80,310)	$ (13)	(80,297)			0
Contributions to consolidated joint venture interests	171						171
Cash distributions to noncontrolling interests	(110)						(110)
Issuance of special dividend paid primarily in stock (in shares)		2,034
Issuance of special dividend paid primarily in stock	123,529		123,529
Cash distributions declared (per common share, none of which represented a return of capital for federal income tax purposes)	(63,312)					(63,312)
Ending Balance at Mar. 31, 2021	$ 4,935,620	$ 705	$ 3,913,258	$ (124,049)	$ (18,897)	$ 918,077	$ 24,594	$ 221,932
Ending Balance (in shares) at Mar. 31, 2021		69,354

Consolidated Statement of Equ_2

Consolidated Statement of Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Cash distribution declared, per common share (in dollars per share)	$ 0.910	$ 0.304

Consolidated Statements of Capi

Consolidated Statements of Capital - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Increase (Decrease) in Partner's Capital
Accounting Standards Update		us-gaap:AccountingStandardsUpdate201613Member		us-gaap:AccountingStandardsUpdate201613Member
Acquisition of subsidiary interest from noncontrolling interest		$ (1,536)
DRSPP proceeds	$ 351	166
Conversion of common units		84
Reallocation of noncontrolling interests in the operating partnership	(26,609)	38,529
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	6,728	5,502
Repurchases of common stock	(80,310)	(219,576)
Contribution to consolidated joint venture interests	171	3,814
Cash distributions to noncontrolling interests	$ (110)	$ (492)
Cash distribution declared, per common share (in dollars per share)	$ 0.910	$ 0.304
Common Stock
Increase (Decrease) in Partner's Capital
DRSPP proceeds (in shares)	5	2
Conversion of common units
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in shares)	113	(32)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	$ 2	$ (1)
Repurchases of common stock (in shares)	(1,306)	(2,562)
Repurchases of common stock	$ (13)	$ (26)
Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Acquisition of subsidiary interest from noncontrolling interest		1,587
Contribution to consolidated joint venture interests	171	3,814
Cash distributions to noncontrolling interests	(110)	(492)
SL Green Operating Partnership
Increase (Decrease) in Partner's Capital
Beginning Balance	4,935,795	5,517,198	$ 5,517,198
Net loss	(5,225)	118,246
Acquisition of subsidiary interest from noncontrolling interest		(1,536)
Other comprehensive income	48,350	(52,383)
Preferred distributions	(3,738)	(3,738)
DRSPP proceeds	351	166
Conversion of common units		84
Reallocation of noncontrolling interests in the operating partnership	(26,609)	38,529
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	6,728	5,502
Repurchases of common stock	(80,310)	(219,576)
Contribution to consolidated joint venture interests	171	3,814
Cash distributions to noncontrolling interests	(110)	$ (492)
Issuance of special distribution paid primarily in units	$ 123,529
Cash distribution declared, per common share (in dollars per share)	$ 0.910	$ 0.304
Cash distributions declared (per common unit, none of which represented a return of capital for federal income tax purposes)	$ (63,312)	$ (22,665)
Ending Balance	4,935,620	5,343,965	4,935,795	$ 5,517,198
SL Green Operating Partnership | Common Stock | Partners' Interest
Increase (Decrease) in Partner's Capital
Beginning Balance	$ 4,755,078	$ 5,247,868	$ 5,247,868
Beginning Balance (units)	68,508	76,956	76,956
Net loss	$ (3,726)	$ 118,539
Acquisition of subsidiary interest from noncontrolling interest		(3,123)
Preferred distributions	$ (3,738)	$ (3,738)
DRSPP proceeds (in shares)	5	2
DRSPP proceeds	$ 351	$ 166
Conversion of common units (in shares)		1
Conversion of common units		$ 84
Reallocation of noncontrolling interests in the operating partnership	$ (26,609)	$ 38,529
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings (in shares)	113	(32)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	$ 6,728	$ 5,502
Repurchases of common stock (in shares)	(1,306)	(2,562)
Repurchases of common stock	$ (80,310)	$ (219,576)
Issuance of special distribution paid primarily in units	$ 123,529
Issuance of special distribution paid primarily in units (in units)	2,034
Cash distributions declared (per common unit, none of which represented a return of capital for federal income tax purposes)	$ (63,312)	(22,665)
Ending Balance	$ 4,707,991	$ 5,122,402	$ 4,755,078	$ 5,247,868
Ending Balance (units)	69,354	74,365	68,508	76,956
SL Green Operating Partnership | Accumulated Other Comprehensive Loss
Increase (Decrease) in Partner's Capital
Beginning Balance	$ (67,247)	$ (28,485)	$ (28,485)
Other comprehensive income	48,350	(52,383)
Ending Balance	(18,897)	(80,868)	(67,247)	$ (28,485)
SL Green Operating Partnership | Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Beginning Balance	26,032	75,883	75,883
Net loss	(1,499)	(293)
Acquisition of subsidiary interest from noncontrolling interest		1,587
Contribution to consolidated joint venture interests	171	3,814
Cash distributions to noncontrolling interests	(110)	(492)
Ending Balance	24,594	80,499	26,032	75,883
Series I Preferred Stock | SL Green Operating Partnership | Preferred Units
Increase (Decrease) in Partner's Capital
Beginning Balance	221,932	221,932	221,932
Ending Balance	$ 221,932	221,932	221,932	221,932
Cumulative Effect, Period of Adoption, Adjustment | SL Green Operating Partnership
Increase (Decrease) in Partner's Capital
Beginning Balance		(39,184)	(39,184)
Ending Balance				(39,184)
Cumulative Effect, Period of Adoption, Adjustment | SL Green Operating Partnership | Common Stock | Partners' Interest
Increase (Decrease) in Partner's Capital
Beginning Balance		(39,184)	(39,184)
Ending Balance				(39,184)
Cumulative Effect, Period of Adoption, Adjusted Balance | SL Green Operating Partnership
Increase (Decrease) in Partner's Capital
Beginning Balance		5,478,014	5,478,014
Ending Balance				5,478,014
Cumulative Effect, Period of Adoption, Adjusted Balance | SL Green Operating Partnership | Common Stock | Partners' Interest
Increase (Decrease) in Partner's Capital
Beginning Balance		$ 5,208,684	$ 5,208,684
Beginning Balance (units)		76,956	76,956
Ending Balance				$ 5,208,684
Ending Balance (units)				76,956
Cumulative Effect, Period of Adoption, Adjusted Balance | SL Green Operating Partnership | Accumulated Other Comprehensive Loss
Increase (Decrease) in Partner's Capital
Beginning Balance		$ (28,485)	$ (28,485)
Ending Balance				$ (28,485)
Cumulative Effect, Period of Adoption, Adjusted Balance | SL Green Operating Partnership | Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Beginning Balance		75,883	75,883
Ending Balance				75,883
Cumulative Effect, Period of Adoption, Adjusted Balance | Series I Preferred Stock | SL Green Operating Partnership | Preferred Units
Increase (Decrease) in Partner's Capital
Beginning Balance		$ 221,932	$ 221,932
Ending Balance				$ 221,932

Consolidated Statements of Ca_2

Consolidated Statements of Capital (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash distribution declared, per common share (in dollars per share)	$ 0.910	$ 0.304
SL Green Operating Partnership
Cash distribution declared, per common share (in dollars per share)	$ 0.910	$ 0.304

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities
Net (loss) income	$ (3,855)	$ 127,114
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	66,770	70,779
Equity in net loss from unconsolidated joint ventures	2,864	12,814
Distributions of cumulative earnings from unconsolidated joint ventures	69	108
Equity in net loss on sale of interest in unconsolidated joint venture interest/real estate	12,629	0
Purchase price and other fair value adjustments	(2,664)	0
Depreciable real estate reserves and impairment	8,241	0
Loss (gain) on sale of real estate, net	1,388	(72,636)
Loan loss reserves and other investment reserves, net of recoveries	0	11,248
Deferred rents receivable	(2,685)	3,717
Non-cash lease expense	3,375	3,390
Other non-cash adjustments	15,564	1,110
Changes in operating assets and liabilities:
Tenant and other receivables	(4,138)	(44,960)
Related party receivables	(683)	(4,711)
Deferred lease costs	(240)	(8,603)
Other assets	(24,354)	(48,130)
Accounts payable, accrued expenses, other liabilities and security deposits	(38,640)	(13,877)
Deferred revenue	4,121	7,622
Lease liability - operating leases	(19,160)	(2,959)
Net cash provided by operating activities	18,602	42,026
Investing Activities
Acquisitions of real estate property	0	(86,846)
Additions to land, buildings and improvements	(49,328)	(101,726)
Investments in unconsolidated joint ventures	(21,027)	(8,906)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	19,692	53,516
Net proceeds from disposition of real estate/joint venture interest	62,800	91,156
Cash assumed from consolidation of real estate investment	9,475	0
Proceeds from sale or redemption of marketable securities	4,528	0
Other investments	(54)	(4,786)
Origination of debt and preferred equity investments	(5,905)	(223,374)
Repayments or redemption of debt and preferred equity investments	0	151,548
Net cash provided by (used in) investing activities	20,181	(129,418)
Financing Activities
Proceeds from mortgages and other loans payable	10,391	101,103
Repayments of mortgages and other loans payable	(362,542)	(102,777)
Proceeds from revolving credit facility and unsecured notes	530,000	1,125,000
Repayments of revolving credit facility and unsecured notes	(10,000)	(315,000)
Proceeds from stock options exercised and DRSPP issuance	351	166
Repurchase of common stock	(84,089)	(219,576)
Redemption of preferred stock	(3,631)	(19,392)
Redemption of OP units	(13,261)	(18,066)
Distributions to noncontrolling interests in other partnerships	(110)	(492)
Contributions from noncontrolling interests in other partnerships	171	3,814
Acquisition of subsidiary interest from noncontrolling interest	0	(1,536)
Distributions to noncontrolling interests in the Operating Partnership	(4,148)	(1,284)
Dividends paid on common and preferred stock	(69,772)	(79,662)
Tax withholdings related to restricted share awards	(2,788)	(4,752)
Deferred loan costs	(288)	(562)
Principal payments of on financing lease liabilities	(255)	0
Net cash (used in) provided by financing activities	(9,971)	466,984
Net increase in cash, cash equivalents, and restricted cash	28,812	379,592
Cash, cash equivalents, and restricted cash at beginning of year	372,795	241,430
Cash, cash equivalents, and restricted cash at end of period	401,607	621,022
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Conversion of units in the Operating Partnership	0	84
Issuance of special dividend paid primarily in stock	123,529	0
Tenant improvements and capital expenditures payable	15,214	602
Fair value adjustment to noncontrolling interest in the Operating Partnership	26,609	0
Consolidation of real estate investment	119,444	0
Reversal of assets held for sale	0	391,664
Extinguishment of debt in connection with property dispositions	53,548	0
Seller financed purchases	0	100,000
Debt and preferred equity investments	10,000	4,638
Removal of fully depreciated commercial real estate properties	1,120	512
Share repurchase payable	3,779	0
Recognition of right of use assets and related lease liabilities	119,711	102,782
Total cash, cash equivalents, and restricted cash	401,607	621,022
SL Green Operating Partnership
Operating Activities
Net (loss) income	(3,855)	127,114
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	66,770	70,779
Equity in net loss from unconsolidated joint ventures	2,864	12,814
Distributions of cumulative earnings from unconsolidated joint ventures	69	108
Equity in net loss on sale of interest in unconsolidated joint venture interest/real estate	12,629	0
Purchase price and other fair value adjustments	(2,664)	0
Depreciable real estate reserves and impairment	8,241	0
Loss (gain) on sale of real estate, net	1,388	(72,636)
Loan loss reserves and other investment reserves, net of recoveries	0	11,248
Deferred rents receivable	(2,685)	3,717
Non-cash lease expense	3,375	3,390
Other non-cash adjustments	15,564	1,110
Changes in operating assets and liabilities:
Tenant and other receivables	(4,138)	(44,960)
Related party receivables	(683)	(4,711)
Deferred lease costs	(240)	(8,603)
Other assets	(24,354)	(48,130)
Accounts payable, accrued expenses, other liabilities and security deposits	(38,640)	(13,877)
Deferred revenue	4,121	7,622
Lease liability - operating leases	(19,160)	(2,959)
Net cash provided by operating activities	18,602	42,026
Investing Activities
Acquisitions of real estate property	0	(86,846)
Additions to land, buildings and improvements	(49,328)	(101,726)
Investments in unconsolidated joint ventures	(21,027)	(8,906)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	19,692	53,516
Net proceeds from disposition of real estate/joint venture interest	62,800	91,156
Cash assumed from consolidation of real estate investment	9,475	0
Proceeds from sale or redemption of marketable securities	4,528	0
Other investments	(54)	(4,786)
Origination of debt and preferred equity investments	(5,905)	(223,374)
Repayments or redemption of debt and preferred equity investments	0	151,548
Net cash provided by (used in) investing activities	20,181	(129,418)
Financing Activities
Proceeds from mortgages and other loans payable	10,391	101,103
Repayments of mortgages and other loans payable	(362,542)	(102,777)
Proceeds from revolving credit facility and unsecured notes	530,000	1,125,000
Repayments of revolving credit facility and unsecured notes	(10,000)	(315,000)
Proceeds from stock options exercised and DRSPP issuance	351	166
Repurchase of common stock	(84,089)	(219,576)
Redemption of preferred stock	(3,631)	(19,392)
Redemption of OP units	(13,261)	(18,066)
Distributions to noncontrolling interests in other partnerships	(110)	(492)
Contributions from noncontrolling interests in other partnerships	171	3,814
Acquisition of subsidiary interest from noncontrolling interest	0	(1,536)
Dividends paid on common and preferred stock	(73,920)	(80,946)
Tax withholdings related to restricted share awards	(2,788)	(4,752)
Deferred loan costs	(288)	(562)
Principal payments of on financing lease liabilities	(255)	0
Net cash (used in) provided by financing activities	(9,971)	466,984
Net increase in cash, cash equivalents, and restricted cash	28,812	379,592
Cash, cash equivalents, and restricted cash at beginning of year	372,795	241,430
Cash, cash equivalents, and restricted cash at end of period	401,607	621,022
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Conversion of units in the Operating Partnership	0	84
Issuance of special dividend paid primarily in stock	123,529	0
Tenant improvements and capital expenditures payable	15,214	602
Fair value adjustment to noncontrolling interest in the Operating Partnership	26,609	0
Consolidation of real estate investment	119,444	0
Reversal of assets held for sale	0	391,664
Extinguishment of debt in connection with property dispositions	53,548	0
Seller financed purchases	0	100,000
Debt and preferred equity investments	10,000	4,638
Removal of fully depreciated commercial real estate properties	1,120	512
Share repurchase payable	3,779	0
Recognition of right of use assets and related lease liabilities	119,711	102,782
Total cash, cash equivalents, and restricted cash	$ 401,607	$ 621,022

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation SL Green Realty Corp., which is referred to as the Company or SL Green, a Maryland corporation, and SL Green Operating Partnership, L.P., which is referred to as SLGOP or the Operating Partnership, a Delaware limited partnership, were formed in June 1997 for the purpose of combining the commercial real estate business of S.L. Green Properties, Inc. and its affiliated partnerships and entities. The Operating Partnership received a contribution of interest in the real estate properties, as well as 95% of the economic interest in the management, leasing and construction companies which are referred to as the Service Corporation. All of the management, leasing and construction services that are provided to the properties that are wholly-owned by us and that are provided to certain joint ventures are conducted through SL Green Management LLC which is 100% owned by the Operating Partnership. The Company has qualified, and expects to qualify in the current fiscal year, as a real estate investment trust, or REIT, under the Internal Revenue Code of 1986, as amended, or the Code, and operates as a self-administered, self-managed REIT. A REIT is a legal entity that holds real estate interests and, through payments of dividends to stockholders, is permitted to minimize the payment of Federal income taxes at the corporate level. Unless the context requires otherwise, all references to "we," "our" and "us" means the Company and all entities owned or controlled by the Company, including the Operating Partnership. Substantially all of our assets are held by, and all of our operations are conducted through, the Operating Partnership. The Company is the sole managing general partner of the Operating Partnership. As of March 31, 2021, noncontrolling investors held, in the aggregate, a 5.65% limited partnership interest in the Operating Partnership. We refer to these interests as the noncontrolling interests in the Operating Partnership. The Operating Partnership is considered a variable interest entity, or VIE, in which we are the primary beneficiary. See Note 11, "Noncontrolling Interests on the Company's Consolidated Financial Statements." On December 4, 2020 our Board of Directors declared an ordinary dividend and a special dividend (together, "the Total Dividend"). The Total Dividend was paid on January 15, 2021 to shareholders of record at the close of business on December 15, 2020 ("the Record Date"). Shareholders had the opportunity to elect to receive the Total Dividend in the form of all cash or all stock, subject to proration if either option was oversubscribed. As a result of the elections made, the cash option was oversubscribed and was prorated. Shareholders who elected to receive cash received, for each share of common stock they owned as of the Record Date, approximately $0.3735 in cash and 0.0279 shares of common stock. Shareholders who elected to receive shares received, for each share of common stock they owned as of the Record Date, approximately 0.0343 shares of common stock. The number of shares issued was calculated based on the volume weighted average trading price of SLG's common stock between January 5-7, 2021, of $58.15 per share. To mitigate the dilutive impact of the common stock issued in the special dividend, the board of directors also authorized a reverse stock split, which was effective after markets closed on January 20, 2021. On January 8, 2021, a committee of the Board of Directors calculated the ratio for the reverse stock split of our issued and outstanding shares of common stock as 1.02918-for-1. After the issuance of the dividend and the completion of the reverse stock split, the number of shares of our common stock outstanding was equivalent to the number of total shares outstanding on the Record Date (not including any issuances or repurchases that occurred following the Record Date, as well as any fractional shares that would have been issued but for which cash-in-lieu was paid). However, on a relative basis, some individual shareholders may have more shares of SLG’s common stock, and some individual shareholders may have fewer shares of our common stock, depending on their individual elections to receive cash or stock and as a result of the cash option being oversubscribed. All share-related references and measurements including the number of shares outstanding, share prices, number of shares repurchased, earnings per share, dividends per share, and share-based compensation awards, have been retroactively adjusted to reflect the reverse stock split for all periods presented in this Quarterly Report on Form 10-Q. As of March 31, 2021, we owned the following interests in properties in the New York metropolitan area, primarily in midtown Manhattan. Our investments located outside of Manhattan are referred to as the Suburban properties: Consolidated Unconsolidated Total Location Property Number of Buildings Approximate Square Feet (unaudited) Number of Buildings Approximate Square Feet (unaudited) Number of Buildings Approximate Square Feet (unaudited) Weighted Average Occupancy (1) (unaudited) Commercial: Manhattan Office 18 10,526,345 9 10,869,183 27 21,395,528 93.4 % Retail 1 10,040 9 301,996 10 312,036 94.6 % Development/Redevelopment 9 1,890,614 3 2,927,782 12 4,818,396 N/A 28 12,426,999 21 14,098,961 49 26,525,960 93.5 % Suburban Office 7 862,800 — — 7 862,800 81.6 % Total commercial properties 35 13,289,799 21 14,098,961 56 27,388,760 93.0 % Residential: Manhattan Residential 1 82,250 8 1,663,774 9 1,746,024 79.1 % Total portfolio 36 13,372,049 29 15,762,735 65 29,134,784 92.2 % (1) The weighted average occupancy for commercial properties represents the total occupied square footage divided by the total square footage at acquisition. The weighted average occupancy for residential properties represents the total occupied units divided by the total available units. As of March 31, 2021, we also managed two office buildings owned by third parties encompassing approximately 2.1 million square feet (unaudited), and held debt and preferred equity investments with a book value of $1.1 billion, excluding $0.1 billion of debt and preferred equity investments and other financing receivables that are included in balance sheet line items other than the Debt and preferred equity investments line item. Partnership Agreement In accordance with the partnership agreement of the Operating Partnership, or the Operating Partnership Agreement, we allocate all distributions and profits and losses in proportion to the percentage of ownership interests of the respective partners, subject to the priority distributions with respect to preferred units and special provisions that apply to LTIP Units. As the managing general partner of the Operating Partnership, we are required to take such reasonable efforts, as determined by us in our sole discretion, to cause the Operating Partnership to distribute sufficient amounts to enable the payment of sufficient dividends by us to minimize any Federal income or excise tax at the Company level. Under the Operating Partnership Agreement, each limited partner has the right to redeem units of limited partnership interests for cash, or if we so elect, shares of SL Green's common stock on a one-for-one basis. Basis of Quarterly Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and notes required by accounting principles generally accepted in the United States for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for the fair presentation of the financial position of the Company and the Operating Partnership at March 31, 2021 and the results of operations for the periods presented have been included. The operating results for the period presented are not necessarily indicative of the results that may be expected for the year ending December 31, 2021. These financial statements should be read in conjunction with the financial statements and accompanying notes included in the Annual Report on Form 10-K for the year ended December 31, 2020 of the Company and the Operating Partnership. The consolidated balance sheet at December 31, 2020 has been derived from the audited financial statements as of that date but does not include all the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. Subsequent Events In April 2021, the Company exercised its option to acquire the fee interest in 461 Fifth Avenue from the ground lessor of the property for a purchase price of $28.0 million. At March 31, 2021, the Company held the leasehold interest in the property. The transaction is expected to close in the second quarter of 2021.

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Principles of Consolidation The consolidated financial statements include our accounts and those of our subsidiaries, which are wholly-owned or controlled by us. Entities which we do not control through our voting interest and entities which are variable interest entities, but where we are not the primary beneficiary, are accounted for under the equity method. See Note 5, "Debt and Preferred Equity Investments" and Note 6, "Investments in Unconsolidated Joint Ventures." All significant intercompany balances and transactions have been eliminated. We consolidate a VIE in which we are considered the primary beneficiary. The primary beneficiary is the entity that has (i) the power to direct the activities that most significantly impact the entity's economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could be significant to the VIE. Investment in Commercial Real Estate Properties We allocate the purchase price of real estate to land and building (inclusive of tenant improvements) and, if determined to be material, intangibles, such as the value of above- and below-market leases and origination costs associated with the in-place leases. We depreciate the amount allocated to building (inclusive of tenant improvements) over their estimated useful lives, which generally range from 3 years to 40 years. We amortize the amount allocated to the above- and below-market leases over the remaining term of the associated lease, which generally range from 1 year to 15 years, and record it as either an increase (in the case of below-market leases) or a decrease (in the case of above-market leases) to rental income. We amortize the amount allocated to the values associated with in-place leases over the expected term of the associated lease, which generally ranges from 1 year to 15 years. If a tenant vacates its space prior to the contractual termination of the lease and no rental payments are being made on the lease, any unamortized balance of the related intangible will be written off. The tenant improvements and origination costs are amortized as an expense over the remaining life of the lease (or charged against earnings if the lease is terminated prior to its contractual expiration date). We assess fair value of the leases based on estimated cash flow projections that utilize appropriate discount rates and available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known trends, and market/economic conditions that may affect the property. To the extent acquired leases contain fixed rate renewal options that are below-market and determined to be material, we amortize such below-market lease value into rental income over the renewal period. The Company classifies those leases under which the Company is the lessee at lease commencement as finance or operating leases. Leases qualify as finance leases if the lease transfers ownership of the asset at the end of the lease term, the lease grants an option to purchase the asset that we are reasonably certain to exercise, the lease term is for a major part of the remaining economic life of the asset, or the present value of the lease payments exceeds substantially all of the fair value of the asset. Leases that do not qualify as finance leases are deemed to be operating leases. At lease commencement the Company records a lease liability which is measured as the present value of the lease payments and a right of use asset which is measured as the amount of the lease liability and any initial direct costs incurred. The Company applies a discount rate to determine the present value of the lease payments. If the rate implicit in the lease is known, the Company uses that rate. If the rate implicit in the lease is not known, the Company uses a discount rate reflective of the Company’s collateralized borrowing rate given the term of the lease. To determine the discount rate, the Company employs a third party specialist to develop an analysis based primarily on the observable borrowing rates of the Company, other REITs, and other corporate borrowers with long-term borrowings. On the consolidated statements of operations, operating leases are expensed through operating lease rent while financing leases are expensed through amortization and interest expense. On the consolidated balance sheets, financing leases include the amounts previously captioned "Properties under capital lease." When applicable, the Company combines the consideration for lease and non-lease components in the calculation of the value of the lease obligation and right-of-use asset. On a periodic basis, we assess whether there are any indications that the value of our real estate properties may be impaired or that their carrying value may not be recoverable. A property's value is considered impaired if management's estimate of the aggregate future cash flows (undiscounted) to be generated by the property is less than the carrying value of the property. To the extent impairment has occurred, the loss will be measured as the excess of the carrying amount of the property over the fair value of the property as calculated in accordance with Accounting Standards Codification, or ASC 820. We also evaluate our real estate properties for impairment when a property has been classified as held for sale. Real estate assets held for sale are valued at the lower of their carrying value or fair value less costs to sell and depreciation expense is no longer recorded. For the three months ended March 31, 2021, we recognized ($1.9 million) of rental revenue for the amortization of aggregate above-market leases in excess of below-market leases resulting from the allocation of the purchase price of the applicable properties. For the three months ended March 31, 2020 , we recognized $1.2 million of rental revenue for the amortization of aggregate below-market leases in excess of above-market leases. The following summarizes our identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases) as of March 31, 2021 and December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Identified intangible assets (included in other assets): Gross amount $ 239,562 $ 215,673 Accumulated amortization (204,386) (190,523) Net (1) $ 35,176 $ 25,150 Identified intangible liabilities (included in deferred revenue): Gross amount $ 242,334 $ 241,409 Accumulated amortization (233,766) (230,479) Net (1) $ 8,568 $ 10,930 (1) As of March 31, 2021 and December 31, 2020, no net intangible assets and no net intangible liabilities were reclassified to assets held for sale or liabilities related to assets held for sale. Cash and Cash Equivalents We consider all highly liquid investments with maturity of three months or less when purchased to be cash equivalents. Restricted Cash Restricted cash primarily consists of security deposits held on behalf of our tenants, interest reserves, as well as capital improvement and real estate tax escrows required under certain loan agreements. Fair Value Measurements See Note 16, "Fair Value Measurements." Investment in Marketable Securities At acquisition, we designate a security as held-to-maturity, available-for-sale, or trading. As of March 31, 2021, we did not have any securities designated as held-to-maturity or trading. We account for our available-for-sale securities at fair value pursuant to ASC 820-10, with the net unrealized gains or losses reported as a component of accumulated other comprehensive income or loss. The cost of marketable securities sold and the amount reclassified out of accumulated other comprehensive income into earnings is determined using the specific identification method. Credit losses are recognized in accordance with ASC 326. At March 31, 2021 and December 31, 2020, we held the following marketable securities (in thousands): March 31, 2021 December 31, 2020 Commercial mortgage-backed securities $ 23,784 $ 28,570 Total marketable securities available-for-sale $ 23,784 $ 28,570 The cost basis of the commercial mortgage-backed securities was $23.0 million and $27.5 million at March 31, 2021 and December 31, 2020, respectively. These securities mature at various times through 2035. All securities were in an unrealized gain position at March 31, 2021 and December 31, 2020 except for one security, which had an unrealized loss of $0.7 million and a fair market value of $7.1 million at March 31, 2021, and an unrealized loss of $0.7 million and a fair value of $7.0 million at December 31, 2020. This marketable security had been in a continuous unrealized loss position for more than 12 months at March 31, 2021 and less than 12 months at December 31, 2020. We do not intend to sell these securities and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases. We held no equity marketable securities as of March 31, 2021 and December 31, 2020. During the three months ended March 31, 2021, we received aggregate net proceeds of $5.0 million from the repayment of one marketable security. We did not dispose of further marketable securities during three months ended March 31, 2021. During the three months ended March 31, 2020, we did not dispose of or receive repayment of any further marketable securities. Investments in Unconsolidated Joint Ventures We assess our investments in unconsolidated joint ventures for recoverability and if it is determined that a loss in value of the investment is other than temporary, we write down the investment to its fair value. We evaluate our equity investments for impairment based on each joint ventures' actual and projected cash flows. We do not believe that the values of any of our equity investments were impaired at March 31, 2021. Deferred Lease Costs Deferred lease costs consist of incremental fees and direct costs that would not have been incurred if the lease had not been obtained and are amortized on a straight-line basis over the related lease term. Lease Classification Lease classification for leases under which the Company is the lessor is evaluated at lease commencement and leases not classified as sales-type leases or direct financing leases are classified as operating leases. Leases qualify as sales-type leases if the contract includes either transfer of ownership clauses, certain purchase options, a lease term representing a major part of the economic life of the asset, or the present value of the lease payments and residual guarantees provided by the lessee exceeds substantially all of the fair value of the asset. Additionally, leasing an asset so specialized that it is not deemed to have any value to the Company at the end of the lease term may also result in classification as a sales-type lease. Leases qualify as direct financing leases when the present value of the lease payments and residual value guarantees provided by the lessee and unrelated third parties exceeds substantially all of the fair value of the asset and collection of the payments is probable. Revenue Recognition Rental revenue for operating leases is recognized on a straight-line basis over the term of the lease. Rental revenue recognition commences when the leased space is available for its intended use by the lessee. To determine whether the leased space is available for its intended use by the lessee, management evaluates whether we are the owner of tenant improvements for accounting purposes or if the tenant is. When management concludes that we are the owner of tenant improvements, rental revenue recognition begins when the tenant takes possession of the finished space, which is when such tenant improvements are substantially complete. In certain instances, when management concludes that we are not the owner of tenant improvements, rental revenue recognition begins when the tenant takes possession of or controls the space. When management concludes that we are the owner of tenant improvements for accounting purposes, we record amounts funded to construct the tenant improvements as a capital asset. For these tenant improvements, we record amounts reimbursed by tenants as a reduction of the capital asset. When management concludes that the tenant is the owner of tenant improvements for accounting purposes, we record our contribution towards those improvements as a lease incentive, which is included in deferred costs, net on our consolidated balance sheets and amortized as a reduction to rental revenue on a straight-line basis over the term of the lease. The excess of rents recognized over amounts contractually due pursuant to the underlying leases are included in deferred rents receivable on the consolidated balance sheets. In addition to base rent, our tenants also generally will pay variable rent which represents their pro rata share of increases in real estate taxes and certain operating expenses for the building over a base year. In some leases, in lieu of paying additional rent based upon increases in certain building operating expenses, the tenant will pay additional rent based upon increases in the wage rate paid to porters over the porters' wage rate in effect during a base year or increases in the consumer price index over the index value in effect during a base year. In addition, many of our leases contain fixed percentage increases over the base rent to cover escalations. Electricity is most often supplied by the landlord either on a sub-metered basis, or rent inclusion basis (i.e., a fixed fee is included in the rent for electricity, which amount may increase based upon increases in electricity rates or increases in electrical usage by the tenant). Base building services other than electricity (such as heat, air conditioning and freight elevator service during business hours, and base building cleaning) are typically provided at no additional cost, with the tenant paying additional rent only for services which exceed base building services or for services which are provided outside normal business hours. These escalations are based on actual expenses incurred in the prior calendar year. If the expenses in the current year are different from those in the prior year, then during the current year, the escalations will be adjusted to reflect the actual expenses for the current year. Rental revenue is recognized if collectability is probable. If collectability of substantially all of the lease payments is assessed as not probable, any difference between the rental revenue recognized to date and the lease payments that have been collected is recognized as a current-period adjustment to rental revenue. A subsequent change in the assessment of collectability to probable may result in a current-period adjustment to rental revenue for any difference between the rental revenue that would have been recognized if collectability had always been assessed as probable and the rental revenue recognized to date. We recognize lease concessions related to COVID-19, such as rent deferrals and abatements, in accordance with the Lease Modification Q&A issued by the FASB in April 2020, which provides entities with the option to elect to account for lease concessions as though the enforceable rights and obligations existed in the original lease. This election is only available when total cash flows resulting from the modified lease are substantially similar to the cash flows in the original lease. When total cash flows resulting from the modified lease are not substantially similar to the cash flows in the original lease, we account for the concession agreement as a new lease. The Company provides its tenants with certain customary services for lease contracts such as common area maintenance and general security. We have elected to combine the non-lease components with the lease components of our operating lease agreements and account for them as a single lease component in accordance with ASC 842. We record a gain or loss on sale of real estate assets when we no longer have a controlling financial interest in the entity owning the real estate, a contract exists with a third party and that third party has control of the assets acquired. Investment income on debt and preferred equity investments is accrued based on the contractual terms of the instruments and when it is deemed collectible. Some debt and preferred equity investments provide for accrual of interest at specified rates, which differ from current payment terms. Interest is recognized on such loans at the accrual rate subject to management's determination that accrued interest is collectible. If management cannot make this determination, interest income above the current pay rate is recognized only upon actual receipt. Deferred origination fees, original issue discounts and loan origination costs, if any, are recognized as an adjustment to interest income over the terms of the related investments using the effective interest method. Fees received in connection with loan commitments are also deferred until the loan is funded and are then recognized over the term of the loan as an adjustment to yield. Discounts or premiums associated with the purchase of loans are amortized or accreted into interest income as a yield adjustment on the effective interest method based on expected cash flows through the expected maturity date of the related investment. If we purchase a debt or preferred equity investment at a discount, intend to hold it until maturity and expect to recover the full value of the investment, we accrete the discount into income as an adjustment to yield over the term of the investment. If we purchase a debt or preferred equity investment at a discount with the intention of foreclosing on the collateral, we do not accrete the discount. For debt investments acquired at a discount for credit quality, the difference between contractual cash flows and expected cash flows at acquisition is not accreted. Anticipated exit fees, the collection of which is expected, are also recognized over the term of the loan as an adjustment to yield. We consider a debt and preferred equity investment to be past due when amounts contractually due have not been paid. Debt and preferred equity investments are placed on a non-accrual status at the earlier of the date at which payments become 90 days past due or when, in the opinion of management, a full recovery of interest income becomes doubtful. Interest income recognition is resumed on any debt or preferred equity investment that is on non-accrual status when such debt or preferred equity investment becomes contractually current and performance is demonstrated to be resumed. We may syndicate a portion of the loans that we originate or sell the loans individually. When a transaction meets the criteria for sale accounting, we recognize gain or loss based on the difference between the sales price and the carrying value of the loan sold. Any related unamortized deferred origination fees, original issue discounts, loan origination costs, discounts or premiums at the time of sale are recognized as an adjustment to the gain or loss on sale, which is included in investment income on the consolidated statement of operations. Any fees received at the time of sale or syndication are recognized as part of investment income. Asset management fees are recognized on a straight-line basis over the term of the asset management agreement. Debt and Preferred Equity Investments Debt and preferred equity investments are presented at the net amount expected to be collected in accordance with ASC 326. An allowance for loan losses is deducted from the amortized cost basis of the financial assets to present the net carrying value at the amount expected to be collected through the expected maturity date of such investments. The expense for loan loss and other investment reserves is the charge to earnings to adjust the allowance for loan losses to the appropriate level. Amounts are written off from the allowance when we de-recognize the related investment either as a result of a sale of the investment or acquisition of equity interests in the collateral. The Company evaluates the amount expected to be collected based on current market and economic conditions, historical loss information, and reasonable and supportable forecasts. The Company's assumptions are derived from both internal data and external data which may include, among others, governmental economic projections for the New York City Metropolitan area, public data on recent transactions and filings for securitized debt instruments. This information is aggregated by asset class and adjusted for duration. Based on these inputs, loans are evaluated at the individual asset level. In certain instances, we may also use a probability-weighted model that considers the likelihood of multiple outcomes and the amount expected to be collected for each outcome. The evaluation of the possible credit deterioration associated with the performance and/or value of the underlying collateral property as well as the financial and operating capability of the borrower/sponsor requires significant judgment, which include both asset level and market assumptions over the relevant time period. In addition, quarterly, the Company assigns each loan a risk rating. Based on a 3-point scale, loans are rated “1” through “3,” from lower risk to higher risk, which ratings are defined as follows: 1 - Low Risk Assets - Low probability of loss, 2 - Watch List Assets - Higher potential for loss, 3 - High Risk Assets - Loss more likely than not. Loans with risk ratings of 2 or above are evaluated to determine whether the expected risk of loss is appropriately captured through the combination of our expectations of current conditions, historical loss information and supportable forecasts described above or whether risk characteristics specific to the loan warrant the use of a probability-weighted model. Financing investments that are classified as held for sale are carried at the expected amount to be collected or fair market value using available market information obtained through consultation with dealers or other originators of such investments as well as discounted cash flow models based on Level 3 data pursuant to ASC 820-10. As circumstances change, management may conclude not to sell an investment designated as held for sale. In such situations, the investment will be reclassified at its expected amount to be collected. Other financing receivables that are included in balance sheet line items other than the Debt and Preferred Equity Investments line are also measured at the net amount expected to be collected. Accrued interest receivable amounts related to these debt and preferred equity investment and other financing receivables are recorded at the net amount expected to be collected within Other assets in the consolidated balance sheets. Accrued interest receivables that are written off are recognized as an expense in loan loss and other investment reserves. Income Taxes SL Green is taxed as a REIT under Section 856(c) of the Code. As a REIT, SL Green generally is not subject to Federal income tax. To maintain its qualification as a REIT, SL Green must distribute at least 90% of its REIT taxable income to its stockholders and meet certain other requirements. If SL Green fails to qualify as a REIT in any taxable year, SL Green will be subject to Federal income tax on its taxable income at regular corporate rates. SL Green may also be subject to certain state, local and franchise taxes. Under certain circumstances, Federal income and excise taxes may be due on its undistributed taxable income. The Operating Partnership is a partnership and, as a result, all income and losses of the partnership are allocated to the partners for inclusion in their respective income tax returns. The only provision for income taxes included in the consolidated statements of operations relates to the Operating Partnership’s consolidated taxable REIT subsidiaries. The Operating Partnership may also be subject to certain state, local and franchise taxes. We have elected, and may elect in the future, to treat certain of our corporate subsidiaries as taxable REIT subsidiaries, or TRSs. In general, TRSs may perform non-customary services for the tenants of the Company, hold assets that we cannot hold directly and generally may engage in any real estate or non-real estate related business. The TRSs generate income, resulting in Federal and state income tax liability for these entities. During the three months ended March 31, 2021, we recorded a Federal, state and local tax provision of $0.7 million. During the three months ended March 31, 2020, we recorded a Federal, state and local provision of $1.1 million. We follow a two-step approach for evaluating uncertain tax positions. Recognition (step one) occurs when an enterprise concludes that a tax position, based solely on its technical merits, is more-likely-than-not to be sustained upon examination. Measurement (step two) determines the amount of benefit that is more-likely-than-not to be realized upon settlement. Derecognition of a tax position that was previously recognized would occur when a company subsequently determines that a tax position no longer meets the more-likely-than-not threshold of being sustained. The use of a valuation allowance as a substitute for derecognition of tax positions is prohibited. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Concentrations of Credit Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash investments, debt and preferred equity investments and accounts receivable. We place our cash investments with high quality financial institutions. The collateral securing our debt and preferred equity investments is located in New York City. See Note 5, "Debt and Preferred Equity Investments." We perform initial and ongoing evaluations of the credit quality of our tenants and require most tenants to provide security deposits or letters of credit. Though these security deposits and letters of credit are insufficient to meet the total value of a tenant's lease obligation, they are a measure of good faith and a potential source of funds to offset the economic costs associated with lost revenue from that tenant and the costs associated with re-tenanting a space. The properties in our real estate portfolio are located in the New York metropolitan area. The tenants located in our buildings operate in various industries. Other than one tenant, Viacom CBS Inc., which accounts for 5.9% of our share of annualized cash rent, no other tenant in our portfolio accounted for more than 5.0% of our share of annualized cash rent, including our share of joint venture annualized rent, at March 31, 2021. For the three months ended March 31, 2021, the following properties contributed more than 5.0% of our annualized cash rent from office properties, including our share of annualized cash rent from joint venture office properties: Property Three months ended March 31, 2021 11 Madison Avenue 9.2% 420 Lexington Avenue (Graybar) 7.2% 1185 Avenue of the Americas 7.1% 1515 Broadway 6.9% 220 East 42nd Street 6.2% 280 Park Avenue 5.8% 485 Lexington Avenue 5.1% Reclassification Certain prior year balances have been reclassified to conform to our current year presentation. Accounting Standards Updates In August 2020, the FASB issued Accounting Standard Update, or "ASU," No. 2020-06 Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40). ASU 2020-06 simplifies the accounting for convertible instruments by reducing the number of accounting models for convertible debt instruments and convertible preferred stock, removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and also simplifies the diluted earnings per share calculation in certain areas. ASU 2020-06 is effective for reporting periods beginning after December 15, 2021, with early adoption permitted. We are currently evaluating the impact of the adoption of ASU 2020-06 on our consolidated financial statements, but do not believe the adoption of this standard will have a material impact on our consolidated financial statements. In March 2020, the FASB issued ASU No. 2020-04 Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting and then in January 2021, the FASB issued ASU No. 2021-01. The amendments provide practical expedients for reference rate reform related activities that impact debt, leases, derivatives and other contracts. The guidance is optional and is effective between March 12, 2020 and December 31, 2022. The guidance may be elected over time as reference rate reform activities occur. During the first quarter of 2020, the Company elected to apply the hedge accounting expedients related to probability and the assessments of effectiveness for future LIBOR-indexed cash flows to assume that the index upon which future hedged transactions will be based matches the index on the corresponding derivatives. Application of these expedients preserves the presentation of derivatives consistent with past presentation. The Company continues to evaluate the impact of the guidance and may apply other elections as applicable as additional changes in the market occur.

Property Acquisitions

Property Acquisitions	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
Property Acquisitions	Property Acquisitions The following table summarizes the properties acquired during the three months ended March 31, 2021: Property Acquisition Date Property Type Approximate Square Feet Gross Asset Valuation (in millions) 885 Third Avenue (1) January 2021 Fee Interest 625,000 $ 387.9 (1) In January 2021, pursuant to the partnership documents of our 885 Third Avenue investment, certain participating rights of the common member expired. As a result, it was determined that this investment is a VIE of which we are the primary beneficiary, and the investment was consolidated in our financial statements. Upon consolidating the entity, the assets and liabilities of the entity were recorded at fair value. Prior to January 2021, the investment was accounted for under the equity method. See Note 6, "Investments in Unconsolidated Joint Ventures" and Note 16, "Fair Value Measurements."

Properties Held for Sale and Pr

Properties Held for Sale and Property Dispositions	3 Months Ended
	Mar. 31, 2021
Discontinued Operations and Disposal Groups [Abstract]
Properties Held for Sale and Property Dispositions	Properties Held for Sale and Property Dispositions Properties Held for Sale As of March 31, 2021, no properties were classified as held for sale. Property Dispositions The following table summarizes the properties disposed of during the three months ended March 31, 2021: Property Disposition Date Property Type Approximate Square Feet Gross Asset Valuation (in millions) (Loss) Gain (in millions) 712 Madison Avenue (1) January 2021 Fee Interest 6,600 $ 43.0 $ (1.4) 133 Greene Street (2) February 2021 Fee Interest 6,425 15.8 0.2 106 Spring Street (2) March 2021 Fee Interest 5,928 35.0 (2.8) (1) Disposition resulted from the buyer exercising its purchase option under a ground lease arrangement. (2) In the first quarter of 2021, the property was foreclosed on by the lender in conjunction with the related debt extinguishment.

Debt and Preferred Equity Inves

Debt and Preferred Equity Investments	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Debt and Preferred Equity Investments	Debt and Preferred Equity Investments Below is a summary of the activity in our debt and preferred equity investments for the three months ended March 31, 2021 and the twelve months ended December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Balance at beginning of year (1) $ 1,076,542 $ 1,580,306 Debt investment originations/fundings/accretion (2) 17,465 389,300 Preferred equity investment originations/accretion (2) 3,195 167,042 Redemptions/sales/syndications/equity ownership/amortization (3) — (1,048,643) Net change in loan loss reserves — (11,463) Balance at end of period (1) $ 1,097,202 $ 1,076,542 (1) Net of unamortized fees, discounts, and premiums. (2) Accretion includes amortization of fees and discounts and paid-in-kind investment income. (3) Certain participations in debt investments that were sold or syndicated, but did not meet the conditions for sale accounting, are included in Other assets and Other liabilities on the consolidated balance sheets. Below is a summary of our debt and preferred equity investments as of March 31, 2021 (dollars in thousands): Floating Rate Fixed Rate Total Carrying Value Senior Financing Weighted Average Yield at End of Period Maturity (1) Type Carrying Value Face Value Interest Rate Carrying Value Face Value Interest Rate Senior Mortgage Debt $ 64,042 $ 64,649 L + 2.00% - 3.50% $ 1,249 $ 1,250 3.50% $ 65,291 $ — 4.74% 2021 - 2022 Junior Mortgage Debt 7,207 12,000 L + 7.25% 42,819 43,000 6.25% 50,026 127,000 7.82% 2021 Mezzanine Debt 281,401 285,179 L + 4.95% - 13.61% 437,503 449,102 2.90% - 14.30% 718,904 4,476,210 5.86% 2021 - 2029 Preferred Equity — — — 262,981 265,052 6.50% - 11.00% 262,981 1,962,750 9.94% 2022 - 2027 Balance at end of period $ 352,650 $ 361,828 $ 744,552 $ 758,404 $ 1,097,202 $ 6,565,960 (1) Excludes available extension options to the extent they have not been exercised as of the date of this filing. The following table is a rollforward of our total allowance for loan losses for the three months ended March 31, 2021 and the twelve months ended December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Balance at beginning of year $ 13,213 $ 1,750 Cumulative adjustment upon adoption of ASC 326 — 27,803 Current period provision for loan loss — 20,693 Write-offs charged against the allowance (1) — (37,033) Balance at end of period (2) $ 13,213 $ 13,213 (1) Includes $19.0 million of charges recorded against investments that were sold during the year ended December 31, 2020. These charges are included in loan loss and other investment reserves, net of recoveries, in our consolidated statements of operations for the year ended December 31, 2020. (2) As of March 31, 2021, we had recorded an allowance for loan loss on all financing receivables on non-accrual except for one debt investment with a carrying value of $225.4 million. At March 31, 2021 and December 31, 2020, all debt and preferred equity investments were performing in accordance with their respective terms, with the exception of one investment with a carrying value, net of reserves, of $6.8 million, as discussed in the Debt Investments table further below. No other financing receivables were 90 days past due at March 31, 2021 and December 31, 2020 with the exception of a $27.7 million financing receivable which was put on nonaccrual in August 2018 as a result of interest default. The following table sets forth the carrying value of our debt and preferred equity investment portfolio by risk rating as of March 31, 2021 and December 31, 2020 (dollars in thousands): Risk Rating March 31, 2021 December 31, 2020 1 - Low Risk Assets - Low probability of loss $ 712,994 $ 695,035 2 - Watch List Assets - Higher potential for loss 367,859 365,167 3 - High Risk Assets - Loss more likely than not 16,349 16,340 $ 1,097,202 $ 1,076,542 The following table sets forth the carrying value of our debt and preferred equity investment portfolio by year of origination and risk rating as of March 31, 2021 (dollars in thousands): As of March 31, 2021 Risk Rating 2021 (1) 2020 (1) 2019 (1) Prior (1) Total 1 - Low Risk Assets - Low probability of loss $ — $ 361,444 $ 56,639 $ 294,911 $ 712,994 2 - Watch List Assets - Higher potential for loss — — 241,285 126,574 367,859 3 - High Risk Assets - Loss more likely than not — — — 16,349 16,349 $ — $ 361,444 $ 297,924 $ 437,834 $ 1,097,202 (1) Year in which the investment was originated or acquired by us or in which a material modification occurred. We have determined that we have one portfolio segment of financing receivables at March 31, 2021 and December 31, 2020 comprised of commercial real estate which is primarily recorded in debt and preferred equity investments. Included in Other assets is an additional amount of financing receivables representing loans to joint venture partners totaling $66.4 million and $66.2 million at March 31, 2021 and December 31, 2020, respectively. The Company recorded provisions for loan losses related to these financing receivables of $0.0 million and $2.8 million for the three months ended March 31, 2021 and 2020, respectively. All of these loans have a risk rating of 2 and were performing in accordance with their respective terms with the exception of one financing receivable, which was put on nonaccrual in August 2018, that has a risk rating of 3 and a carrying value at March 31, 2021 of $2.5 million. Debt Investments As of March 31, 2021 and December 31, 2020, we held the following debt investments with an aggregate weighted average current yield of 5.90% at March 31, 2021 (dollars in thousands): Loan Type March 31, 2021 March 31, 2021 Senior March 31, 2021 Carrying Value (1) December 31, 2020 (1) Maturity (2) Fixed Rate Investments: Junior Mortgage (3a) $ — $ 67,000 $ 42,820 $ 32,888 July 2021 Mezzanine Loan — 15,000 3,500 3,500 September 2021 Mortgage/Mezzanine Loan — 63,750 56,246 56,244 October 2021 Mezzanine Loan — 280,000 41,652 41,057 August 2022 Mezzanine Loan (4) — 359,237 225,367 225,204 June 2023 Mezzanine Loan (3b)(5) — 105,000 13,366 13,366 June 2024 Mezzanine Loan — 95,000 30,000 30,000 January 2025 Mezzanine Loan — 1,712,750 55,250 55,250 June 2027 Mezzanine Loan — 85,000 20,000 20,000 December 2029 Total fixed rate $ — $ 2,782,737 $ 488,201 $ 477,509 Floating Rate Investments: Mezzanine Loan (6) $ — $ 275,000 $ 49,992 $ 49,956 April 2021 Junior Mortgage Participation/Mezzanine Loan — 60,000 15,742 15,733 July 2021 Mezzanine Loan 5,761 177,415 36,639 35,318 July 2021 Mezzanine Loan — 61,744 29,130 29,106 July 2021 Mezzanine Loan (3c) — 1,115,000 129,330 127,915 March 2022 Mortgage and Mezzanine Loan 6,769 — 60,922 60,532 May 2022 Mortgage and Mezzanine Loan 42,117 — 15,918 14,011 December 2022 Mezzanine Loan 52,288 71,314 21,560 19,889 May 2023 Total floating rate $ 106,935 $ 1,760,473 $ 359,233 $ 352,460 Allowance for loan loss $ — $ — $ (13,213) $ (13,213) Total $ 106,935 $ 4,543,210 $ 834,221 $ 816,756 (1) Carrying value is net of discounts, premiums, original issue discounts and deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options. (3) Carrying value is net of the following amounts that were sold or syndicated, which are included in Other assets and Other liabilities on the consolidated balance sheets as a result of the transfers not meeting the conditions for sale accounting: (a) $66.6 million (b) $12.0 million, and (c) $0.4 million. (4) This loan was put on non-accrual in July 2020 and remains on non-accrual at March 31, 2021. No investment income has been recognized subsequent to it being put on non-accrual. (5) This loan went into default and was put on non-accrual in June 2020 and remains on non-accrual at March 31, 2021. No investment income has been recognized subsequent to it being put on non-accrual. The Company is in discussions with the borrower. (6) In April 2021, the maturity date of this loan was extended one year to April 2022. Preferred Equity Investments As of March 31, 2021 and December 31, 2020, we held the following preferred equity investments with an aggregate weighted average current yield of 9.94% at March 31, 2021 (dollars in thousands): Type March 31, 2021 March 31, 2021 Senior March 31, 2021 Carrying Value (1) December 31, 2020 Carrying Value (1) Mandatory Redemption (2) Preferred Equity $ — $ 1,712,750 $ 156,169 $ 154,691 June 2022 Preferred Equity — 250,000 106,812 105,095 February 2027 Total Preferred Equity $ — $ 1,962,750 $ 262,981 $ 259,786 Allowance for loan loss $ — $ — $ — $ — Total $ — $ 1,962,750 $ 262,981 $ 259,786 (1) Carrying value is net of deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options.

Investments in Unconsolidated J

Investments in Unconsolidated Joint Ventures	3 Months Ended
	Mar. 31, 2021
Equity Method Investments and Joint Ventures [Abstract]
Investments in Unconsolidated Joint Ventures	Investments in Unconsolidated Joint Ventures We have investments in several real estate joint ventures with various partners. As of March 31, 2021, the book value of these investments was $3.7 billion, net of investments with negative book values totaling $92.4 million for which we have an implicit commitment to fund future capital needs. As of March 31, 2021 and December 31, 2020, 800 Third Avenue, 21 East 66th Street, 605 West 42nd Street, and certain properties within the Stonehenge Portfolio are VIEs in which we are not the primary beneficiary. Our net equity investment in these VIEs was $132.7 million and $134.0 million as of March 31, 2021 and December 31, 2020, respectively. Our maximum loss is limited to the amount of our equity investment in these VIEs. See the "Principles of Consolidation" section of Note 2, "Significant Accounting Policies." All other investments below are voting interest entities. As we do not control the joint ventures listed below, we account for them under the equity method of accounting. The table below provides general information on each of our joint ventures as of March 31, 2021: Property Partner Ownership (1) Economic (1) Unaudited Approximate Square Feet 100 Park Avenue Prudential Real Estate Investors 49.90% 49.90% 834,000 717 Fifth Avenue Wharton Properties/Private Investor 10.92% 10.92% 119,500 800 Third Avenue Private Investors 60.52% 60.52% 526,000 919 Third Avenue New York State Teacher's Retirement System 51.00% 51.00% 1,454,000 11 West 34th Street Private Investor/Wharton Properties 30.00% 30.00% 17,150 280 Park Avenue Vornado Realty Trust 50.00% 50.00% 1,219,158 1552-1560 Broadway (2) Wharton Properties 50.00% 50.00% 57,718 10 East 53rd Street Canadian Pension Plan Investment Board 55.00% 55.00% 354,300 21 East 66th Street (3) Private Investors 32.28% 32.28% 13,069 650 Fifth Avenue (4) Wharton Properties 50.00% 50.00% 69,214 121 Greene Street Wharton Properties 50.00% 50.00% 7,131 Stonehenge Portfolio Various Various Various 1,439,016 605 West 42nd Street (5) The Moinian Group 20.00% 20.00% 927,358 11 Madison Avenue PGIM Real Estate 60.00% 60.00% 2,314,000 400 East 57th Street (6) BlackRock, Inc and Stonehenge Partners 51.00% 41.00% 290,482 One Vanderbilt National Pension Service of Korea/Hines Interest LP 71.01% 71.01% 1,657,198 Worldwide Plaza RXR Realty / New York REIT / Private Investor 24.35% 24.35% 2,048,725 1515 Broadway Allianz Real Estate of America 56.87% 56.87% 1,750,000 2 Herald Square Israeli Institutional Investor 51.00% 51.00% 369,000 Property Partner Ownership (1) Economic (1) Unaudited Approximate Square Feet 115 Spring Street Private Investor 51.00% 51.00% 5,218 15 Beekman (7) A fund managed by Meritz Alternative Investment Management 20.00% 20.00% 221,884 85 Fifth Avenue Wells Fargo 36.30% 36.30% 12,946 One Madison Avenue (8) National Pension Service of Korea/Hines Interest LP 50.50% 50.50% 1,048,700 (1) Ownership interest and economic interest represent the Company's interests in the joint venture as of March 31, 2021. Changes in ownership or economic interests within the current year are disclosed in the notes below. (2) The joint venture also owns a long-term leasehold interest in the retail space and certain other spaces at 1560 Broadway, which is adjacent to 1552 Broadway. (3) We hold a 32.28% interest in three retail units and one residential unit at the property and a 16.14% interest in three residential units at the property. (4) The joint venture owns a long-term leasehold interest in the retail space at 650 Fifth Avenue. (5) In April 2021, we entered into contract to sell our interest in the property. This transaction is expected to close in the second quarter of 2021 subject to customary closing conditions. (6) In October 2016, we sold a 49% interest in this property. Our interest in the property was sold within a consolidated joint venture owned 90% by the Company and 10% by Stonehenge. The transaction resulted in the deconsolidation of the venture's remaining 51% interest in the property. Our joint venture with Stonehenge remains consolidated resulting in the combined 51% interest being shown within investments in unconsolidated joint ventures on our balance sheet. In April 2021, we entered into contract to sell our interest in the property. In connection with this contract, we recorded a charge of $5.7 million, which is included in depreciable real estate reserves and impairment in the consolidated statements of operations. This transaction is expected to close in the third quarter of 2021 subject to customary closing conditions. (7) In 2020, the Company formed a joint venture, which then entered into a long-term sublease with the Company. (8) In 2020, the Company admitted partners to the One Madison Avenue development project, which resulted in the Company no longer retaining a controlling interest in the entity, as defined in ASC 810, and the deconsolidation of our remaining 50.5% interest. We recorded our investment at fair value, which resulted in the recognition of a fair value adjustment of $187.5 million in 2020 and a fair value adjustment of $2.7 million during the three months ended March 31, 2021. The fair value of our investment was determined by the terms of the joint venture agreement governing the capitalization of the project. The partners have committed aggregate equity to the project totaling no less than $492.2 million and their ownership interest in the joint venture is based on their capital contributions, up to an aggregate maximum of 49.5%. At March 31, 2021, the total of the two partners' ownership interests based on equity contributed was 9.0%. Disposition of Joint Venture Interests or Properties The following table summarizes the investments in unconsolidated joint ventures disposed of during the three months ended March 31, 2021: Property Ownership Interest Disposed Disposition Date Gross Asset Valuation (in thousands) Gain (Loss) on Sale (in thousands) (1) 885 Third Avenue (2) N/A January 2021 N/A N/A 55 West 46th Street - Tower 46 25.0% March 2021 $ 275.0 $ (15.2) (1) Represents the Company's share of the gain or loss. (2) In January 2021, pursuant to the partnership documents of our 885 Third Avenue investment, certain participating rights of the common member expired. As a result, it was determined that we are the primary beneficiary of the VIE and the investment was consolidated in our financial statements. See Note 3, "Property Acquisitions." Joint Venture Mortgages and Other Loans Payable We generally finance our joint ventures with non-recourse debt. In certain cases we may provide guarantees or master leases for tenant space, which terminate upon the satisfaction of specified circumstances or repayment of the underlying loans. The mortgage notes and other loans payable collateralized by the respective joint venture properties and assignment of leases at March 31, 2021 and December 31, 2020, respectively, are as follows (dollars in thousands): Property Economic (1) Initial Maturity Final Maturity Date (2) Interest Rate (3) March 31, 2021 December 31, 2020 Fixed Rate Debt: 717 Fifth Avenue (mortgage) 10.92 % July 2022 July 2022 4.45 % $ 300,000 $ 300,000 717 Fifth Avenue (mezzanine) 10.92 % July 2022 July 2022 5.50 % 355,328 355,328 650 Fifth Avenue (mortgage) 50.00 % October 2022 October 2022 4.46 % 210,000 210,000 650 Fifth Avenue (mezzanine) 50.00 % October 2022 October 2022 5.45 % 65,000 65,000 21 East 66th Street 32.28 % April 2023 April 2028 3.60 % 12,000 12,000 Property Economic (1) Initial Maturity Final Maturity Date (2) Interest Rate (3) March 31, 2021 December 31, 2020 919 Third Avenue 51.00 % June 2023 June 2023 5.12 % 500,000 500,000 1515 Broadway 56.87 % March 2025 March 2025 3.93 % 815,876 820,607 11 Madison Avenue 60.00 % September 2025 September 2025 3.84 % 1,400,000 1,400,000 800 Third Avenue 60.52 % February 2026 February 2026 3.37 % 177,000 177,000 400 East 57th Street (4) 41.00 % November 2026 November 2026 3.00 % 97,024 97,024 Worldwide Plaza 24.35 % November 2027 November 2027 3.98 % 1,200,000 1,200,000 Stonehenge Portfolio (5) Various Various Various 3.50 % 195,899 195,899 885 Third Avenue (6) — 272,000 Total fixed rate debt $ 5,328,127 $ 5,604,858 Floating Rate Debt: 280 Park Avenue 50.00 % September 2021 September 2024 L+ 1.73 % $ 1,200,000 $ 1,200,000 One Vanderbilt (7) 71.01 % September 2021 September 2023 L+ 2.50 % 1,283,292 1,210,329 1552 Broadway 50.00 % October 2021 October 2022 L+ 2.65 % 195,000 195,000 2 Herald Square 51.00 % November 2021 November 2023 L+ 1.45 % 214,500 214,500 11 West 34th Street 30.00 % January 2022 January 2023 L+ 1.45 % 23,000 23,000 121 Greene Street (8) 50.00 % November 2022 November 2022 L+ 2.00 % 13,771 15,000 115 Spring Street 51.00 % September 2023 September 2023 L+ 3.40 % 65,550 65,550 100 Park Avenue 49.90 % December 2023 December 2025 L+ 2.25 % 360,000 360,000 15 Beekman (9) 20.00 % January 2024 July 2025 L+ 1.50 % 19,165 11,212 10 East 53rd Street 55.00 % February 2025 February 2025 L+ 1.35 % 220,000 220,000 One Madison Avenue (10) 50.50 % November 2025 November 2026 L+ 3.35 % 40,104 — 605 West 42nd Street (11) 20.00 % August 2027 August 2027 L+ 1.44 % 550,000 550,000 21 East 66th Street 32.28 % June 2033 June 2033 T+ 2.75 % 666 677 55 West 46th Street — 192,524 Total floating rate debt $ 4,185,048 $ 4,257,792 Total joint venture mortgages and other loans payable $ 9,513,175 $ 9,862,650 Deferred financing costs, net (98,252) (113,446) Total joint venture mortgages and other loans payable, net $ 9,414,923 $ 9,749,204 (1) Economic interest represents the Company's interests in the joint venture as of March 31, 2021. Changes in ownership or economic interests, if any, within the current year are disclosed in the notes to the investment in unconsolidated joint ventures table above. (2) Reflects exercise of all available options. The ability to exercise extension options may be subject to certain tests based on the operating performance of the property. (3) Interest rates as of March 31, 2021, taking into account interest rate hedges in effect during the period. Floating rate debt is presented with the stated spread over the 30-day LIBOR ("L") or 1-year Treasury ("T"). (4) In April 2021, we entered into a contract to sell our interest in the property. This transaction is expected to close in the third quarter of 2021 subject to customary closing conditions. (5) Comprised of three mortgages totaling $132.4 million that mature in April 2028 and two mortgages totaling $63.5 million that mature in July 2029. (6) This loan was repaid in the first quarter of 2021, and as of March 31, 2021, the property is consolidated in our financial statements. See Note 3, "Property Acquisitions." (7) This loan is a $1.75 billion construction facility with reductions in interest cost based on meeting certain conditions, the first of which has been satisfied, and has an initial term of three years with two one year extension options. Advances under the loan are subject to costs incurred. In conjunction with the loan, we provided partial guarantees for interest and principal payments, the amounts of which are based on certain construction milestones and operating metrics. (8) In March 2021, the maturity date of this loan was extended by one year. (9) This loan is a $125.0 million construction facility. Advances under the loan are subject to costs incurred. (10) The loan is a $1.25 billion construction facility with an initial term of five years with one one year extension option. Advances under the loan are subject to costs incurred. In conjunction with the loan, we provided partial guarantees for interest and principal payments, the amounts of which are based on certain construction milestones and operating metrics. (11) In April 2021, we entered into contract to sell our interest in the property. This transaction is expected to close in the second quarter of 2021 subject to customary closing conditions. We are entitled to receive fees for providing management, leasing, construction supervision and asset management services to certain of our joint ventures. We earned $2.4 million from these services, net of our ownership share of the joint ventures, for the three months ended March 31, 2021. We earned $2.2 million from these services, net of our ownership share of the joint ventures, for the three months ended March 31, 2020. In addition, we have the ability to earn incentive fees based on the ultimate financial performance of certain of the joint venture properties. The combined balance sheets for the unconsolidated joint ventures, at March 31, 2021 and December 31, 2020 are as follows (in thousands): March 31, 2021 December 31, 2020 Assets (1) Commercial real estate property, net $ 15,243,331 $ 16,143,880 Cash and restricted cash 317,753 357,076 Tenant and other receivables, related party receivables, and deferred rents receivable 412,203 403,883 Other assets 1,950,444 2,001,612 Total assets $ 17,923,731 $ 18,906,451 Liabilities and equity (1) Mortgages and other loans payable, net $ 9,414,923 $ 9,749,204 Deferred revenue 1,311,191 1,341,571 Lease liabilities 985,622 1,002,563 Other liabilities 373,400 464,107 Equity 5,838,595 6,349,006 Total liabilities and equity $ 17,923,731 $ 18,906,451 Company's investments in unconsolidated joint ventures $ 3,698,701 $ 3,823,322 (1) At March 31, 2021, $174.2 million of net unamortized basis differences between the amount at which our investments are carried and our share of equity in net assets of the underlying property will be amortized through equity in net income (loss) from unconsolidated joint ventures over the remaining life of the underlying items having given rise to the differences. The combined statements of operations for the unconsolidated joint ventures, from acquisition date through the three months ended March 31, 2021 and 2020, are as follows (in thousands): Three Months Ended March 31, 2021 2020 Total revenues $ 301,541 $ 282,520 Operating expenses 46,233 51,590 Real estate taxes 54,592 53,372 Operating lease rent 5,644 6,361 Interest expense, net of interest income 78,749 86,324 Amortization of deferred financing costs 6,384 4,814 Depreciation and amortization 114,879 98,584 Total expenses 306,481 301,045 Net loss before gain on sale $ (4,940) $ (18,525) Company's equity in net loss from unconsolidated joint ventures $ (2,864) $ (12,814)

Deferred Costs

Deferred Costs	3 Months Ended
	Mar. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred Costs	Deferred Costs Deferred costs at March 31, 2021 and December 31, 2020 consisted of the following (in thousands): March 31, 2021 December 31, 2020 Deferred leasing costs $ 448,197 $ 447,002 Less: accumulated amortization (277,945) (269,834) Deferred costs, net $ 170,252 $ 177,168

Mortgages and Other Loans Payab

Mortgages and Other Loans Payable	3 Months Ended
	Mar. 31, 2021
Mortgages and Other Loans Payable
Mortgages and Other Loans Payable	Mortgages and Other Loans Payable The mortgages and other loans payable collateralized by the respective properties and assignment of leases or debt investments at March 31, 2021 and December 31, 2020, respectively, were as follows (dollars in thousands): Property Initial Maturity Final Maturity Date (1) Interest Rate (2) March 31, 2021 December 31, 2020 Fixed Rate Debt: 100 Church Street July 2022 July 2022 4.68% $ 203,697 $ 204,875 420 Lexington Avenue October 2024 October 2040 3.99% 292,672 294,035 Landmark Square January 2027 January 2027 4.90% 100,000 100,000 485 Lexington Avenue February 2027 February 2027 4.25% 450,000 450,000 1080 Amsterdam (3) February 2027 February 2027 3.59% 34,773 34,773 Total fixed rate debt $ 1,081,142 $ 1,083,683 Floating Rate Debt: 185 Broadway (4) November 2021 November 2023 L+ 2.85% $ 168,870 $ 158,478 609 Fifth Avenue March 2022 March 2022 L+ 2.95% 57,651 57,651 220 East 42nd Street June 2023 June 2025 L+ 2.75% 510,000 510,000 719 Seventh Avenue September 2023 September 2023 L+ 1.20% 50,000 50,000 133 Greene Street — 15,523 106 Spring Street — 38,025 FHLB Facility — 10,000 FHLB Facility — 15,000 FHLB Facility — 35,000 712 Madison Avenue — 28,000 2017 Master Repurchase Agreement (5) — — Total floating rate debt $ 786,521 $ 917,677 Total mortgages and other loans payable $ 1,867,663 $ 2,001,360 Deferred financing costs, net of amortization (18,962) (21,388) Total mortgages and other loans payable, net $ 1,848,701 $ 1,979,972 (1) Reflects exercise of all available options. The ability to exercise extension options may be subject to certain tests based on the operating performance of the property. (2) Interest rate as of March 31, 2021, taking into account interest rate hedges in effect during the period. Floating rate debt is presented with the stated spread over the 30-day LIBOR, unless otherwise specified. (3) The loan is comprised of a $33.9 million mortgage loan and $0.9 million mezzanine loan with a fixed interest rate of 350 basis points and 700 basis points, respectively, for the first five years and is prepayable without penalty at the end of fifth year. (4) This loan is a $225.0 million construction facility, with reductions in interest cost based on meeting certain conditions, and has an initial three year term with two one year extension options. Advances under the loan are subject to incurred costs and funded equity requirements. (5) In June 2020, we exercised a one year extension option which extended the maturity date to June 2021. At March 31, 2021, there was no outstanding balance on the $400 million facility. At March 31, 2021 and December 31, 2020, the gross book value of the properties and debt and preferred equity investments collateralizing the mortgages and other loans payable was approximately $2.4 billion and $2.5 billion, respectively. Federal Home Loan Bank of New York ("FHLB") Facility As of December 31, 2020, the Company’s wholly-owned subsidiary, Ticonderoga Insurance Company, or Ticonderoga, a Vermont licensed captive insurance company, was a member of the Federal Home Loan Bank of New York, or FHLBNY. As a member, Ticonderoga was able to borrow funds from the FHLBNY in the form of secured advances that bore interest at a floating rate. As a result of a Final Ruling from the Federal Housing Finance Authority, the regulator of the Federal Home Loan Bank system, all captive insurance company memberships were terminated as of February 2021. As such, all advances to Ticonderoga were repaid prior to such termination. Master Repurchase Agreement The Company entered into a Master Repurchase Agreement, or MRA, known as the 2017 MRA, which provides us with the ability to sell certain mortgage investments with a simultaneous agreement to repurchase the same at a certain date or on demand. We seek to mitigate risks associated with our repurchase agreement by managing the credit quality of our assets, early repayments, interest rate volatility, liquidity, and market value. The margin call provisions under our repurchase facility permit valuation adjustments based on capital markets activity, and are not limited to collateral-specific credit marks. To monitor credit risk associated with our debt investments, our asset management team regularly reviews our investment portfolio and is in contact with our borrowers in order to monitor the collateral and enforce our rights as necessary. The risk associated with potential margin calls is further mitigated by our ability to collateralize the facility with additional assets from our portfolio of debt investments, our ability to satisfy margin calls with cash or cash equivalents and our access to additional liquidity. As of March 31, 2021, there have been no margin calls on the 2017 MRA. In April 2018, we increased the maximum facility capacity from $300.0 million to $400.0 million. The facility bears interest on a floating rate basis at a spread to 30-day LIBOR based on the pledged collateral and advance rate and is scheduled to mature in June 2021, with a one-year extension option. At March 31, 2021, the facility had no outstanding balance. 2017 Credit Facility In November 2017, we entered into an amendment to the credit facility, referred to as the 2017 credit facility, that was originally entered into by the Company in November 2012, or the 2012 credit facility. As of March 31, 2021, the 2017 credit facility consisted of a $1.5 billion revolving credit facility, a $1.3 billion term loan (or "Term Loan A"), and a $200.0 million term loan (or "Term Loan B") with maturity dates of March 31, 2022, March 31, 2023, and November 21, 2024, respectively. The revolving credit facility has two six-month, as-of-right extension options to March 31, 2023. We also have an option, subject to customary conditions, to increase the capacity of the credit facility to $4.5 billion at any time prior to the maturity dates for the revolving credit facility and term loans without the consent of existing lenders, by obtaining additional commitments from our existing lenders and other financial institutions. As of March 31, 2021, the 2017 credit facility bore interest at a spread over 30-day LIBOR ranging from (i) 82.5 basis points to 155 basis points for loans under the revolving credit facility, (ii) 90 basis points to 175 basis points for loans under Term Loan A, and (iii) 85 basis points to 165 basis points for loans under Term Loan B, in each case based on the credit rating assigned to the senior unsecured long term indebtedness of the Company. In instances where there are either only two ratings available or where there are more than two and the difference between them is one rating category, the applicable rating shall be the highest rating. In instances where there are more than two ratings and the difference between the highest and the lowest is two or more rating categories, then the applicable rating used is the average of the highest two, rounded down if the average is not a recognized category. At March 31, 2021, the applicable spread was 100 basis points for the revolving credit facility, 110 basis points for Term Loan A, and 100 basis points for Term Loan B. We are required to pay quarterly in arrears a 12.5 to 30 basis point facility fee on the total commitments under the revolving credit facility based on the credit rating assigned to the senior unsecured long term indebtedness of the Company. As of March 31, 2021, the facility fee was 20 basis points. As of March 31, 2021, we had $16.5 million of outstanding letters of credit, $630.0 million drawn under the revolving credit facility and $1.5 billion outstanding under the term loan facilities, with total undrawn capacity of $0.9 billion under the 2017 credit facility. At March 31, 2021 and December 31, 2020, the revolving credit facility had a carrying value of $625.8 million and $105.3 million, respectively, net of deferred financing costs. At March 31, 2021 and December 31, 2020, the term loan facilities had a carrying value of $1.5 billion and $1.5 billion, respectively, net of deferred financing costs. The Company and the Operating Partnership are borrowers jointly and severally obligated under the 2017 credit facility. The 2017 credit facility includes certain restrictions and covenants (see Restrictive Covenants below). Senior Unsecured Notes The following table sets forth our senior unsecured notes and other related disclosures as of March 31, 2021 and December 31, 2020, respectively, by scheduled maturity date (dollars in thousands): Issuance March 31, 2021 March 31, 2021 December 31, Interest Rate (1) Initial Term Maturity Date August 7, 2018 (2) (3) $ 350,000 $ 350,000 $ 350,000 1.52 % 3 August 2021 October 5, 2017 (2) 500,000 499,830 499,803 3.25 % 5 October 2022 November 15, 2012 (4) 300,000 301,817 302,086 4.50 % 10 December 2022 December 17, 2015 (5) 100,000 100,000 100,000 4.27 % 10 December 2025 $ 1,250,000 $ 1,251,647 $ 1,251,889 Deferred financing costs, net (3,025) (3,670) $ 1,250,000 $ 1,248,622 $ 1,248,219 (1) Interest rate as of March 31, 2021, taking into account interest rate hedges in effect during the period. (2) Issued by the Operating Partnership with the Company as the guarantor. (3) The notes are subject to redemption at the Company's option, in whole but not in part, at a redemption price equal to 100% of the principal amount of the notes, plus unpaid accrued interest thereon to the redemption date. In April 2020, the Company entered into $350.0 million of fixed rate interest swaps at a rate of 0.54375% through August 2021. (4) In October 2017, the Company and the Operating Partnership as co-obligors issued an additional $100.0 million of 4.50% senior unsecured notes due December 2022. The notes were priced at 105.334% of par. (5) Issued by the Company and the Operating Partnership as co-obligors. Restrictive Covenants The terms of the 2017 credit facility and certain of our senior unsecured notes include certain restrictions and covenants which may limit, among other things, our ability to pay dividends, make certain types of investments, incur additional indebtedness, incur liens and enter into negative pledge agreements and dispose of assets, and which require compliance with financial ratios relating to the maximum ratio of total indebtedness to total asset value, a minimum ratio of EBITDA to fixed charges, a maximum ratio of secured indebtedness to total asset value and a maximum ratio of unsecured indebtedness to unencumbered asset value. The dividend restriction referred to above provides that we will not, during any time when a default is continuing, make distributions with respect to common stock or other equity interests, except to enable the Company to continue to qualify as a REIT for Federal income tax purposes. As of March 31, 2021 and December 31, 2020, we were in compliance with all such covenants. Junior Subordinated Deferrable Interest Debentures In June 2005, the Company and the Operating Partnership issued $100.0 million in unsecured trust preferred securities through a newly formed trust, SL Green Capital Trust I, or the Trust, which is a wholly-owned subsidiary of the Operating Partnership. The securities mature in 2035 and bear interest at a floating rate of 125 basis points over the three-month LIBOR. Interest payments may be deferred for a period of up to eight consecutive quarters if the Operating Partnership exercises its right to defer such payments. The Trust preferred securities are redeemable at the option of the Operating Partnership, in whole or in part, with no prepayment premium. We do not consolidate the Trust even though it is a variable interest entity as we are not the primary beneficiary. Because the Trust is not consolidated, we have recorded the debt on our consolidated balance sheets and the related payments are classified as interest expense. Principal Maturities Combined aggregate principal maturities of mortgages and other loans payable, the 2017 credit facility, trust preferred securities, senior unsecured notes and our share of joint venture debt as of March 31, 2021, including as-of-right extension options, were as follows (in thousands): Scheduled Mortgages and Other Loans Payable Revolving Unsecured Term Loans Trust Senior Total Joint Remaining 2021 $ 8,031 $ 168,870 $ — $ — $ — $ 350,000 $ 526,901 $ 1,126,896 2022 8,765 255,435 — — — 800,000 1,064,200 227,701 2023 6,594 560,000 630,000 1,300,000 — — 2,496,594 491,066 2024 5,280 272,749 — 200,000 — — 478,029 620,843 2025 823 — — — — 100,000 100,823 1,403,266 Thereafter 924 580,192 — — 100,000 — 681,116 552,813 $ 30,417 $ 1,837,246 $ 630,000 $ 1,500,000 $ 100,000 $ 1,250,000 $ 5,347,663 $ 4,422,585 Consolidated interest expense, excluding capitalized interest, was comprised of the following (in thousands): Three Months Ended March 31, 2021 2020 Interest expense before capitalized interest $ 39,868 $ 56,813 Interest on financing leases 1,492 1,663 Interest capitalized (17,583) (20,483) Interest income (389) (499) Interest expense, net $ 23,388 $ 37,494

Corporate Indebtedness

Corporate Indebtedness	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Corporate Indebtedness	Mortgages and Other Loans Payable The mortgages and other loans payable collateralized by the respective properties and assignment of leases or debt investments at March 31, 2021 and December 31, 2020, respectively, were as follows (dollars in thousands): Property Initial Maturity Final Maturity Date (1) Interest Rate (2) March 31, 2021 December 31, 2020 Fixed Rate Debt: 100 Church Street July 2022 July 2022 4.68% $ 203,697 $ 204,875 420 Lexington Avenue October 2024 October 2040 3.99% 292,672 294,035 Landmark Square January 2027 January 2027 4.90% 100,000 100,000 485 Lexington Avenue February 2027 February 2027 4.25% 450,000 450,000 1080 Amsterdam (3) February 2027 February 2027 3.59% 34,773 34,773 Total fixed rate debt $ 1,081,142 $ 1,083,683 Floating Rate Debt: 185 Broadway (4) November 2021 November 2023 L+ 2.85% $ 168,870 $ 158,478 609 Fifth Avenue March 2022 March 2022 L+ 2.95% 57,651 57,651 220 East 42nd Street June 2023 June 2025 L+ 2.75% 510,000 510,000 719 Seventh Avenue September 2023 September 2023 L+ 1.20% 50,000 50,000 133 Greene Street — 15,523 106 Spring Street — 38,025 FHLB Facility — 10,000 FHLB Facility — 15,000 FHLB Facility — 35,000 712 Madison Avenue — 28,000 2017 Master Repurchase Agreement (5) — — Total floating rate debt $ 786,521 $ 917,677 Total mortgages and other loans payable $ 1,867,663 $ 2,001,360 Deferred financing costs, net of amortization (18,962) (21,388) Total mortgages and other loans payable, net $ 1,848,701 $ 1,979,972 (1) Reflects exercise of all available options. The ability to exercise extension options may be subject to certain tests based on the operating performance of the property. (2) Interest rate as of March 31, 2021, taking into account interest rate hedges in effect during the period. Floating rate debt is presented with the stated spread over the 30-day LIBOR, unless otherwise specified. (3) The loan is comprised of a $33.9 million mortgage loan and $0.9 million mezzanine loan with a fixed interest rate of 350 basis points and 700 basis points, respectively, for the first five years and is prepayable without penalty at the end of fifth year. (4) This loan is a $225.0 million construction facility, with reductions in interest cost based on meeting certain conditions, and has an initial three year term with two one year extension options. Advances under the loan are subject to incurred costs and funded equity requirements. (5) In June 2020, we exercised a one year extension option which extended the maturity date to June 2021. At March 31, 2021, there was no outstanding balance on the $400 million facility. At March 31, 2021 and December 31, 2020, the gross book value of the properties and debt and preferred equity investments collateralizing the mortgages and other loans payable was approximately $2.4 billion and $2.5 billion, respectively. Federal Home Loan Bank of New York ("FHLB") Facility As of December 31, 2020, the Company’s wholly-owned subsidiary, Ticonderoga Insurance Company, or Ticonderoga, a Vermont licensed captive insurance company, was a member of the Federal Home Loan Bank of New York, or FHLBNY. As a member, Ticonderoga was able to borrow funds from the FHLBNY in the form of secured advances that bore interest at a floating rate. As a result of a Final Ruling from the Federal Housing Finance Authority, the regulator of the Federal Home Loan Bank system, all captive insurance company memberships were terminated as of February 2021. As such, all advances to Ticonderoga were repaid prior to such termination. Master Repurchase Agreement The Company entered into a Master Repurchase Agreement, or MRA, known as the 2017 MRA, which provides us with the ability to sell certain mortgage investments with a simultaneous agreement to repurchase the same at a certain date or on demand. We seek to mitigate risks associated with our repurchase agreement by managing the credit quality of our assets, early repayments, interest rate volatility, liquidity, and market value. The margin call provisions under our repurchase facility permit valuation adjustments based on capital markets activity, and are not limited to collateral-specific credit marks. To monitor credit risk associated with our debt investments, our asset management team regularly reviews our investment portfolio and is in contact with our borrowers in order to monitor the collateral and enforce our rights as necessary. The risk associated with potential margin calls is further mitigated by our ability to collateralize the facility with additional assets from our portfolio of debt investments, our ability to satisfy margin calls with cash or cash equivalents and our access to additional liquidity. As of March 31, 2021, there have been no margin calls on the 2017 MRA. In April 2018, we increased the maximum facility capacity from $300.0 million to $400.0 million. The facility bears interest on a floating rate basis at a spread to 30-day LIBOR based on the pledged collateral and advance rate and is scheduled to mature in June 2021, with a one-year extension option. At March 31, 2021, the facility had no outstanding balance. 2017 Credit Facility In November 2017, we entered into an amendment to the credit facility, referred to as the 2017 credit facility, that was originally entered into by the Company in November 2012, or the 2012 credit facility. As of March 31, 2021, the 2017 credit facility consisted of a $1.5 billion revolving credit facility, a $1.3 billion term loan (or "Term Loan A"), and a $200.0 million term loan (or "Term Loan B") with maturity dates of March 31, 2022, March 31, 2023, and November 21, 2024, respectively. The revolving credit facility has two six-month, as-of-right extension options to March 31, 2023. We also have an option, subject to customary conditions, to increase the capacity of the credit facility to $4.5 billion at any time prior to the maturity dates for the revolving credit facility and term loans without the consent of existing lenders, by obtaining additional commitments from our existing lenders and other financial institutions. As of March 31, 2021, the 2017 credit facility bore interest at a spread over 30-day LIBOR ranging from (i) 82.5 basis points to 155 basis points for loans under the revolving credit facility, (ii) 90 basis points to 175 basis points for loans under Term Loan A, and (iii) 85 basis points to 165 basis points for loans under Term Loan B, in each case based on the credit rating assigned to the senior unsecured long term indebtedness of the Company. In instances where there are either only two ratings available or where there are more than two and the difference between them is one rating category, the applicable rating shall be the highest rating. In instances where there are more than two ratings and the difference between the highest and the lowest is two or more rating categories, then the applicable rating used is the average of the highest two, rounded down if the average is not a recognized category. At March 31, 2021, the applicable spread was 100 basis points for the revolving credit facility, 110 basis points for Term Loan A, and 100 basis points for Term Loan B. We are required to pay quarterly in arrears a 12.5 to 30 basis point facility fee on the total commitments under the revolving credit facility based on the credit rating assigned to the senior unsecured long term indebtedness of the Company. As of March 31, 2021, the facility fee was 20 basis points. As of March 31, 2021, we had $16.5 million of outstanding letters of credit, $630.0 million drawn under the revolving credit facility and $1.5 billion outstanding under the term loan facilities, with total undrawn capacity of $0.9 billion under the 2017 credit facility. At March 31, 2021 and December 31, 2020, the revolving credit facility had a carrying value of $625.8 million and $105.3 million, respectively, net of deferred financing costs. At March 31, 2021 and December 31, 2020, the term loan facilities had a carrying value of $1.5 billion and $1.5 billion, respectively, net of deferred financing costs. The Company and the Operating Partnership are borrowers jointly and severally obligated under the 2017 credit facility. The 2017 credit facility includes certain restrictions and covenants (see Restrictive Covenants below). Senior Unsecured Notes The following table sets forth our senior unsecured notes and other related disclosures as of March 31, 2021 and December 31, 2020, respectively, by scheduled maturity date (dollars in thousands): Issuance March 31, 2021 March 31, 2021 December 31, Interest Rate (1) Initial Term Maturity Date August 7, 2018 (2) (3) $ 350,000 $ 350,000 $ 350,000 1.52 % 3 August 2021 October 5, 2017 (2) 500,000 499,830 499,803 3.25 % 5 October 2022 November 15, 2012 (4) 300,000 301,817 302,086 4.50 % 10 December 2022 December 17, 2015 (5) 100,000 100,000 100,000 4.27 % 10 December 2025 $ 1,250,000 $ 1,251,647 $ 1,251,889 Deferred financing costs, net (3,025) (3,670) $ 1,250,000 $ 1,248,622 $ 1,248,219 (1) Interest rate as of March 31, 2021, taking into account interest rate hedges in effect during the period. (2) Issued by the Operating Partnership with the Company as the guarantor. (3) The notes are subject to redemption at the Company's option, in whole but not in part, at a redemption price equal to 100% of the principal amount of the notes, plus unpaid accrued interest thereon to the redemption date. In April 2020, the Company entered into $350.0 million of fixed rate interest swaps at a rate of 0.54375% through August 2021. (4) In October 2017, the Company and the Operating Partnership as co-obligors issued an additional $100.0 million of 4.50% senior unsecured notes due December 2022. The notes were priced at 105.334% of par. (5) Issued by the Company and the Operating Partnership as co-obligors. Restrictive Covenants The terms of the 2017 credit facility and certain of our senior unsecured notes include certain restrictions and covenants which may limit, among other things, our ability to pay dividends, make certain types of investments, incur additional indebtedness, incur liens and enter into negative pledge agreements and dispose of assets, and which require compliance with financial ratios relating to the maximum ratio of total indebtedness to total asset value, a minimum ratio of EBITDA to fixed charges, a maximum ratio of secured indebtedness to total asset value and a maximum ratio of unsecured indebtedness to unencumbered asset value. The dividend restriction referred to above provides that we will not, during any time when a default is continuing, make distributions with respect to common stock or other equity interests, except to enable the Company to continue to qualify as a REIT for Federal income tax purposes. As of March 31, 2021 and December 31, 2020, we were in compliance with all such covenants. Junior Subordinated Deferrable Interest Debentures In June 2005, the Company and the Operating Partnership issued $100.0 million in unsecured trust preferred securities through a newly formed trust, SL Green Capital Trust I, or the Trust, which is a wholly-owned subsidiary of the Operating Partnership. The securities mature in 2035 and bear interest at a floating rate of 125 basis points over the three-month LIBOR. Interest payments may be deferred for a period of up to eight consecutive quarters if the Operating Partnership exercises its right to defer such payments. The Trust preferred securities are redeemable at the option of the Operating Partnership, in whole or in part, with no prepayment premium. We do not consolidate the Trust even though it is a variable interest entity as we are not the primary beneficiary. Because the Trust is not consolidated, we have recorded the debt on our consolidated balance sheets and the related payments are classified as interest expense. Principal Maturities Combined aggregate principal maturities of mortgages and other loans payable, the 2017 credit facility, trust preferred securities, senior unsecured notes and our share of joint venture debt as of March 31, 2021, including as-of-right extension options, were as follows (in thousands): Scheduled Mortgages and Other Loans Payable Revolving Unsecured Term Loans Trust Senior Total Joint Remaining 2021 $ 8,031 $ 168,870 $ — $ — $ — $ 350,000 $ 526,901 $ 1,126,896 2022 8,765 255,435 — — — 800,000 1,064,200 227,701 2023 6,594 560,000 630,000 1,300,000 — — 2,496,594 491,066 2024 5,280 272,749 — 200,000 — — 478,029 620,843 2025 823 — — — — 100,000 100,823 1,403,266 Thereafter 924 580,192 — — 100,000 — 681,116 552,813 $ 30,417 $ 1,837,246 $ 630,000 $ 1,500,000 $ 100,000 $ 1,250,000 $ 5,347,663 $ 4,422,585 Consolidated interest expense, excluding capitalized interest, was comprised of the following (in thousands): Three Months Ended March 31, 2021 2020 Interest expense before capitalized interest $ 39,868 $ 56,813 Interest on financing leases 1,492 1,663 Interest capitalized (17,583) (20,483) Interest income (389) (499) Interest expense, net $ 23,388 $ 37,494

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Cleaning/ Security/ Messenger and Restoration Services Alliance Building Services, or Alliance, and its affiliates are partially owned by Gary Green, a son of Stephen L. Green, who serves as a member and as the chairman emeritus of our board of directors, and provide services to certain properties owned by us. Alliance’s affiliates include First Quality Maintenance, L.P., or First Quality, Classic Security LLC, Bright Star Couriers LLC and Onyx Restoration Works, and provide cleaning, extermination, security, messenger, and restoration services, respectively. In addition, First Quality has the non-exclusive opportunity to provide cleaning and related services to individual tenants at our properties on a basis separately negotiated with any tenant seeking such additional services. The Service Corporation has entered into an arrangement with Alliance whereby it will receive a profit participation above a certain threshold for services provided by Alliance to certain tenants at certain buildings above the base services specified in their lease agreements. Income earned from the profit participation, which is included in Other income on the consolidated statements of operations, was $0.3 million and $0.9 million for the three months ended March 31, 2021 and 2020, respectively. We also recorded expenses, inclusive of capitalized expenses, of $2.3 million and $3.9 million for the three months ended March 31, 2021 and 2020, respectively, for these services (excluding services provided directly to tenants). Management Fees S.L. Green Management Corp., a consolidated entity, receives property management fees from an entity in which Stephen L. Green owns an interest. We received management fees from this entity of $0.1 million and $0.2 million for the three months ended March 31, 2021 and 2020, respectively. One Vanderbilt Investment In December 2016, we entered into agreements with entities owned and controlled by our Chairman and CEO, Marc Holliday, and our President, Andrew Mathias, pursuant to which they agreed to make an investment in our One Vanderbilt project at the appraised fair market value for the interests acquired. This investment entitles these entities to receive approximately 1.50% - 1.80% and 1.00% - 1.20%, respectively, of any profits realized by the Company from its One Vanderbilt project in excess of the Company’s capital contributions. The entities have no right to any return of capital. Accordingly, subject to previously disclosed repurchase rights, these interests will have no value and will not entitle these entities to any amounts (other than limited distributions to cover tax liabilities incurred) unless and until the Company has received distributions from the One Vanderbilt project in excess of the Company’s aggregate investment in the project. In the event that the Company does not realize a profit on its investment in the project (or would not realize a profit based on the value at the time the interests are repurchased), the entities owned and controlled by Messrs. Holliday and Mathias will lose the entire amount of their investment. The entities owned and controlled by Messrs. Holliday and Mathias paid $1.4 million and $1.0 million, respectively, which equal the fair market value of the interests acquired as of the date the investment agreements were entered into as determined by an independent third party appraisal that we obtained. One Vanderbilt Lease In November 2018, we entered into a lease agreement with the One Vanderbilt joint venture covering certain floors at the property. In March 2021, the lease commenced and we relocated our corporate headquarters to the leased space. For the three months ended March 31, 2021, we recorded $0.1 million of rent expense under the lease, which is included in Marketing, general and administrative in the consolidated statements of operations. See Note 19, “Commitments and Contingencies.” Other We are entitled to receive fees for providing management, leasing, construction supervision and asset management services to certain of our joint ventures as further described in Note 6, "Investments in Unconsolidated Joint Ventures." Amounts due from joint ventures and related parties at March 31, 2021 and December 31, 2020 consisted of the following (in thousands): March 31, 2021 December 31, 2020 Due from joint ventures $ 26,500 $ 27,006 Other 7,810 7,651 Related party receivables $ 34,310 $ 34,657

Noncontrolling Interests on the

Noncontrolling Interests on the Company's Consolidated Financial Statements	3 Months Ended
	Mar. 31, 2021
Noncontrolling Interest [Abstract]
Noncontrolling Interests on the Company's Consolidated Financial Statements	Noncontrolling Interests on the Company's Consolidated Financial Statements Noncontrolling interests represent the common and preferred units of limited partnership interest in the Operating Partnership not held by the Company as well as third party equity interests in our other consolidated subsidiaries. Noncontrolling interests in the Operating Partnership are shown in the mezzanine equity while the noncontrolling interests in our other consolidated subsidiaries are shown in the equity section of the Company’s consolidated financial statements. Common Units of Limited Partnership Interest in the Operating Partnership As of March 31, 2021 and December 31, 2020, the noncontrolling interest unit holders owned 5.65%, or 4,156,282 units, and 5.44%, or 3,938,823 units, of the Operating Partnership, respectively, inclusive of retroactive adjustments to reflect the reverse stock split effectuated by SL Green in January 2021. As of March 31, 2021, 4,156,282 shares of our common stock were reserved for issuance upon the redemption of units of limited partnership interest of the Operating Partnership. Noncontrolling interests in the Operating Partnership is recorded at the greater of its cost basis or fair market value based on the closing stock price of our common stock at the end of the reporting period. Below is a summary of the activity relating to the noncontrolling interests in the Operating Partnership for the three months ended March 31, 2021 and the twelve months ended December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Balance at beginning of period $ 358,262 $ 409,862 Distributions (4,148) (12,652) Issuance of common units 4,483 12,018 Redemption and conversion of common units (13,261) (36,085) Net (loss) income (476) 20,016 Accumulated other comprehensive income (loss) allocation 2,655 (2,299) Fair value adjustment 26,609 (32,598) Balance at end of period $ 374,124 $ 358,262 Preferred Units of Limited Partnership Interest in the Operating Partnership Below is a summary of the preferred units of limited partnership interest in the Operating Partnership as of March 31, 2021: Issuance Stated Distribution Rate Number of Units Authorized Number of Units Issued Number of Units Outstanding Annual Dividend Per Unit (1) Liquidation Preference Per Unit (2) Conversion Price Per Unit (3) Date of Issuance Series A (4) 3.50 % 109,161 109,161 109,161 $ 35.0000 $ 1,000.00 $ — August 2015 Series F 7.00% 60 60 60 $ 70.0000 $ 1,000.00 $ 29.12 January 2007 Series G (5) 4.50% 1,902,000 1,902,000 718,697 $ 1.1250 $ 25.00 $ 88.50 January 2012 Series K 3.50% 700,000 563,954 341,677 $ 0.8750 $ 25.00 $ 134.67 August 2014 Series L 4.00% 500,000 378,634 372,634 $ 1.0000 $ 25.00 $ — August 2014 Series M 3.75% 1,600,000 1,600,000 96,357 $ 0.9375 $ 25.00 $ — February 2015 Series P 4.00% 200,000 200,000 200,000 $ 1.0000 $ 25.00 $ — July 2015 Series Q 3.50% 268,000 268,000 268,000 $ 0.8750 $ 25.00 $ 148.95 July 2015 Series R 3.50% 400,000 400,000 400,000 $ 0.8750 $ 25.00 $ 154.89 August 2015 Series S 4.00% 1,077,280 1,077,280 1,077,280 $ 1.0000 $ 25.00 $ — August 2015 Series V 3.50% 40,000 40,000 40,000 $ 0.8750 $ 25.00 $ — May 2019 Series W (6) (6) 1 1 1 (6) (6) (6) January 2020 (1) Dividends are cumulative, subject to certain provisions. (2) Units are redeemable at any time at par for cash at the option of the unitholder unless otherwise specified. (3) If applicable, units are convertible into a number of common units of limited partnership interest in the Operating Partnership equal to (i) the liquidation preference plus accumulated and unpaid distributions on the conversion date divided by (ii) the amount shown in the table. (4) Issued through a consolidated subsidiary. The units are convertible on a one-for-one basis, into the Series B Preferred Units of limited partnership interest, or the Subsidiary Series B Preferred Units. The Subsidiary Series B Preferred Units can be converted at any time, at the option of the unitholder, into a number of common stock equal to 6.71348 shares of common stock for each Subsidiary Series B Preferred Unit. As of March 31, 2021, no Subsidiary Series B Preferred Units have been issued. (5) Common units of limited partnership interest in the Operating Partnership issued in a conversion may be redeemed in exchange for our common stock on a 1-to-1 basis. The Series G Preferred Units also provide the holder with the right to require the Operating Partnership to repurchase the Series G Preferred Units for cash before January 31, 2022. (6) The Series W preferred unit was issued in January 2020 in exchange for the then-outstanding Series O preferred unit. The holder of the Series W preferred unit is entitled to quarterly dividends in an amount calculated as (i) 1,350 multiplied by (ii) the current distribution per common unit of limited partnership in SL Green Operating Partnership. The holder has the right to require the Operating Partnership to repurchase the Series W unit for cash, or convert the Series W unit for Class B units, in each case at a price that is determined based on the closing price of the Company's common stock at the time such right is exercised. The unit's liquidation preference is the fair market value of the unit plus accrued distributions at the time of a liquidation event. Below is a summary of the activity relating to the preferred units in the Operating Partnership for the three months ended March 31, 2021 and the twelve months ended December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Balance at beginning of period $ 202,169 $ 283,285 Issuance of preferred units — — Redemption of preferred units (3,631) (82,750) Dividends paid on preferred units (1,731) (6,163) Accrued dividends on preferred units 1,696 7,797 Balance at end of period $ 198,503 $ 202,169

Stockholders' Equity of the Com

Stockholders' Equity of the Company	3 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Stockholders' Equity of the Company	Stockholders’ Equity of the Company Common Stock Our authorized capital stock consists of 260,000,000 shares, $0.01 par value per share, consisting of 160,000,000 shares of common stock, $0.01 par value per share, 75,000,000 shares of excess stock, at $0.01 par value per share, and 25,000,000 shares of preferred stock, par value $0.01 per share. As of March 31, 2021, 69,353,606 shares of common stock and no shares of excess stock were issued and outstanding. On December 4, 2020 our Board of Directors declared an ordinary dividend and a special dividend (together, "the Total Dividend"). The Total Dividend was paid on January 15, 2021 to shareholders of record at the close of business on December 15, 2020 ("the Record Date"). Shareholders had the opportunity to elect to receive the Total Dividend in the form of all cash or all stock, subject to proration if either option was oversubscribed. Shareholders who elected to receive cash received, for each share of common stock they owned as of the Record Date, approximately $0.3735 in cash and 0.0279 shares of common stock. Shareholders who elected to receive shares received, for each share of common stock they owned as of the Record Date, approximately 0.0343 shares of common stock. The number of shares issued was calculated based on the volume weighted average trading price of SLG's common stock between January 5-7, 2021, of $58.15 per share. To mitigate the dilutive impact of the common stock issued in the special dividend, the board of directors also authorized a reverse stock split, which was effective after markets closed on January 20, 2021. On January 8, 2021, a committee of the Board of Directors calculated the ratio for the reverse stock split of our issued and outstanding shares of common stock as 1.02918-for-1. After the issuance of the dividend and the completion of the reverse stock split, the number of shares of our common stock outstanding was equivalent to the number of total shares outstanding on the Record Date (not including any issuances or repurchases that occurred following the Record Date, as well as any fractional shares that would have been issued but for which cash-in-lieu was paid). However, on a relative basis, some individual shareholders may have more shares of SLG’s common stock, and some individual shareholders may have fewer shares of our common stock, depending on their individual elections to receive cash or stock and as a result of the cash option being oversubscribed. All share-related references and measurements including the number of shares outstanding, share prices, number of shares repurchased, earnings per share, dividends per share, and share-based compensation awards, have been retroactively adjusted to reflect the reverse stock split for all periods presented in this Quarterly Report on Form 10-Q. Share Repurchase Program In August 2016, our Board of Directors approved a $1.0 billion share repurchase program under which we can buy shares of our common stock. The Board of Directors has since authorized five separate $500.0 million increases to the size of the share repurchase program in the fourth quarter of 2017, second quarter of 2018, fourth quarter of 2018, fourth quarter of 2019, and fourth quarter of 2020 bringing the total program size to $3.5 billion. At March 31, 2021, share repurchases, excluding the redemption of OP units, executed under the program were as follows: Period Shares repurchased Average price paid per share Cumulative number of shares repurchased as part of the repurchase plan or programs Year ended 2017 8,105,881 $104.61 8,105,881 Year ended 2018 9,468,617 $99.03 17,574,498 Year ended 2019 4,465,857 $86.06 22,040,355 Year Ended 2020 8,529,279 $62.39 30,569,634 Three months ended March 31, 2021 1,306,460 $61.46 31,876,094 Perpetual Preferred Stock We have 9,200,000 shares of our 6.50% Series I Cumulative Redeemable Preferred Stock, or the Series I Preferred Stock, outstanding with a mandatory liquidation preference of $25.00 per share. The Series I Preferred stockholders receive annual dividends of $1.625 per share paid on a quarterly basis and dividends are cumulative, subject to certain provisions. We are entitled to redeem the Series I Preferred Stock at any time, in whole or from time to time in part, at par for cash. In August 2012, we received $221.9 million in net proceeds from the issuance of the Series I Preferred Stock, which were recorded net of underwriters' discount and issuance costs, and contributed the net proceeds to the Operating Partnership in exchange for 9,200,000 units of 6.50% Series I Cumulative Redeemable Preferred Units of limited partnership interest, or the Series I Preferred Units. Dividend Reinvestment and Stock Purchase Plan ("DRSPP") In February 2018, the Company filed a registration statement with the SEC for our dividend reinvestment and stock purchase plan, or DRSPP, which automatically became effective upon filing. The Company registered 3,500,000 shares of our common stock under the DRSPP. The DRSPP commenced on September 24, 2001. The following table summarizes SL Green common stock issued, and proceeds received from dividend reinvestments and/or stock purchases under the DRSPP for the three months ended March 31, 2021 and 2020, respectively (dollars in thousands): Three Months Ended March 31, 2021 2020 Shares of common stock issued 5,483 1,727 Dividend reinvestments/stock purchases under the DRSPP $ 351 $ 166 Earnings per Share We use the two-class method of computing earnings per share (“EPS”), which is an earnings allocation formula that determines EPS for common stock and any participating securities according to dividends declared (whether paid or unpaid). Under the two-class method, basic EPS is computed by dividing the income available to common stockholders by the weighted-average number of common stock shares outstanding for the period. Diluted EPS reflects the potential dilution that could occur from share equivalent activity. SL Green's earnings per share for the three months ended March 31, 2021 and 2020 are computed as follows (in thousands): Three Months Ended March 31, Numerator 2021 2020 Basic Earnings: Net (loss) income attributable to SL Green common stockholders $ (7,464) $ 114,801 Less: distributed earnings allocated to participating securities (371) (113) Less: undistributed earnings allocated to participating securities — (464) Net (loss) income attributable to SL Green common stockholders (numerator for basic earnings per share) $ (7,835) $ 114,224 Add back: dilutive effect of earnings allocated to participating securities 371 113 Add back: undistributed earnings allocated to participating securities — 464 Add back: effect of dilutive securities (redemption of units to common shares) (476) 6,202 Net (loss) income attributable to SL Green common stockholders (numerator for diluted earnings per share) $ (7,940) $ 121,003 Three Months Ended March 31, Denominator 2021 2020 Basic Shares: Weighted average common stock outstanding 69,010 75,656 Effect of Dilutive Securities: Operating Partnership units redeemable for common shares 4,148 4,220 Stock-based compensation plans 595 476 Contingently issuable shares from special dividend declared December 4, 2020 and issued January 15, 2021 317 — Diluted weighted average common stock outstanding 74,070 80,352 The Company has excluded 1,159,343 common stock equivalents from the calculation of diluted shares outstanding for the three months ended March 31, 2021, as they were anti-dilutive. The Company has excluded 1,170,579 common stock equivalents from the calculation of diluted shares outstanding for the three months ended March 31, 2020, as they were anti-dilutive. The following tables set forth the changes in accumulated other comprehensive loss by component as of March 31, 2021 (in thousands): Net unrealized loss on derivative instruments ( 1 ) SL Green’s share of joint venture net unrealized loss on derivative instruments ( 2 ) Net unrealized gain (loss) on marketable securities Total Balance at December 31, 2020 $ (57,415) $ (10,853) $ 1,021 $ (67,247) Other comprehensive income before reclassifications 9,771 33,024 (247) 42,548 Amounts reclassified from accumulated other comprehensive loss 4,196 1,606 — 5,802 Balance at March 31, 2021 $ (43,448) $ 23,777 $ 774 $ (18,897) (1) Amount reclassified from accumulated other comprehensive loss is included in interest expense in the respective consolidated statements of operations. As of March 31, 2021 and December 31, 2020, the deferred net gains from these terminated hedges, which is included in accumulated other comprehensive loss relating to net unrealized loss on derivative instrument, was $(0.6) million and $(0.5) million, respectively. (2) Amount reclassified from accumulated other comprehensive loss is included in equity in net loss from unconsolidated joint ventures in the respective consolidated statements of operations.

Partners' Capital of the Operat

Partners' Capital of the Operating Partnership	3 Months Ended
	Mar. 31, 2021
Stockholders' Equity
Partners' Capital of the Operating Partnership	Stockholders’ Equity of the Company Common Stock Our authorized capital stock consists of 260,000,000 shares, $0.01 par value per share, consisting of 160,000,000 shares of common stock, $0.01 par value per share, 75,000,000 shares of excess stock, at $0.01 par value per share, and 25,000,000 shares of preferred stock, par value $0.01 per share. As of March 31, 2021, 69,353,606 shares of common stock and no shares of excess stock were issued and outstanding. On December 4, 2020 our Board of Directors declared an ordinary dividend and a special dividend (together, "the Total Dividend"). The Total Dividend was paid on January 15, 2021 to shareholders of record at the close of business on December 15, 2020 ("the Record Date"). Shareholders had the opportunity to elect to receive the Total Dividend in the form of all cash or all stock, subject to proration if either option was oversubscribed. Shareholders who elected to receive cash received, for each share of common stock they owned as of the Record Date, approximately $0.3735 in cash and 0.0279 shares of common stock. Shareholders who elected to receive shares received, for each share of common stock they owned as of the Record Date, approximately 0.0343 shares of common stock. The number of shares issued was calculated based on the volume weighted average trading price of SLG's common stock between January 5-7, 2021, of $58.15 per share. To mitigate the dilutive impact of the common stock issued in the special dividend, the board of directors also authorized a reverse stock split, which was effective after markets closed on January 20, 2021. On January 8, 2021, a committee of the Board of Directors calculated the ratio for the reverse stock split of our issued and outstanding shares of common stock as 1.02918-for-1. After the issuance of the dividend and the completion of the reverse stock split, the number of shares of our common stock outstanding was equivalent to the number of total shares outstanding on the Record Date (not including any issuances or repurchases that occurred following the Record Date, as well as any fractional shares that would have been issued but for which cash-in-lieu was paid). However, on a relative basis, some individual shareholders may have more shares of SLG’s common stock, and some individual shareholders may have fewer shares of our common stock, depending on their individual elections to receive cash or stock and as a result of the cash option being oversubscribed. All share-related references and measurements including the number of shares outstanding, share prices, number of shares repurchased, earnings per share, dividends per share, and share-based compensation awards, have been retroactively adjusted to reflect the reverse stock split for all periods presented in this Quarterly Report on Form 10-Q. Share Repurchase Program In August 2016, our Board of Directors approved a $1.0 billion share repurchase program under which we can buy shares of our common stock. The Board of Directors has since authorized five separate $500.0 million increases to the size of the share repurchase program in the fourth quarter of 2017, second quarter of 2018, fourth quarter of 2018, fourth quarter of 2019, and fourth quarter of 2020 bringing the total program size to $3.5 billion. At March 31, 2021, share repurchases, excluding the redemption of OP units, executed under the program were as follows: Period Shares repurchased Average price paid per share Cumulative number of shares repurchased as part of the repurchase plan or programs Year ended 2017 8,105,881 $104.61 8,105,881 Year ended 2018 9,468,617 $99.03 17,574,498 Year ended 2019 4,465,857 $86.06 22,040,355 Year Ended 2020 8,529,279 $62.39 30,569,634 Three months ended March 31, 2021 1,306,460 $61.46 31,876,094 Perpetual Preferred Stock We have 9,200,000 shares of our 6.50% Series I Cumulative Redeemable Preferred Stock, or the Series I Preferred Stock, outstanding with a mandatory liquidation preference of $25.00 per share. The Series I Preferred stockholders receive annual dividends of $1.625 per share paid on a quarterly basis and dividends are cumulative, subject to certain provisions. We are entitled to redeem the Series I Preferred Stock at any time, in whole or from time to time in part, at par for cash. In August 2012, we received $221.9 million in net proceeds from the issuance of the Series I Preferred Stock, which were recorded net of underwriters' discount and issuance costs, and contributed the net proceeds to the Operating Partnership in exchange for 9,200,000 units of 6.50% Series I Cumulative Redeemable Preferred Units of limited partnership interest, or the Series I Preferred Units. Dividend Reinvestment and Stock Purchase Plan ("DRSPP") In February 2018, the Company filed a registration statement with the SEC for our dividend reinvestment and stock purchase plan, or DRSPP, which automatically became effective upon filing. The Company registered 3,500,000 shares of our common stock under the DRSPP. The DRSPP commenced on September 24, 2001. The following table summarizes SL Green common stock issued, and proceeds received from dividend reinvestments and/or stock purchases under the DRSPP for the three months ended March 31, 2021 and 2020, respectively (dollars in thousands): Three Months Ended March 31, 2021 2020 Shares of common stock issued 5,483 1,727 Dividend reinvestments/stock purchases under the DRSPP $ 351 $ 166 Earnings per Share We use the two-class method of computing earnings per share (“EPS”), which is an earnings allocation formula that determines EPS for common stock and any participating securities according to dividends declared (whether paid or unpaid). Under the two-class method, basic EPS is computed by dividing the income available to common stockholders by the weighted-average number of common stock shares outstanding for the period. Diluted EPS reflects the potential dilution that could occur from share equivalent activity. SL Green's earnings per share for the three months ended March 31, 2021 and 2020 are computed as follows (in thousands): Three Months Ended March 31, Numerator 2021 2020 Basic Earnings: Net (loss) income attributable to SL Green common stockholders $ (7,464) $ 114,801 Less: distributed earnings allocated to participating securities (371) (113) Less: undistributed earnings allocated to participating securities — (464) Net (loss) income attributable to SL Green common stockholders (numerator for basic earnings per share) $ (7,835) $ 114,224 Add back: dilutive effect of earnings allocated to participating securities 371 113 Add back: undistributed earnings allocated to participating securities — 464 Add back: effect of dilutive securities (redemption of units to common shares) (476) 6,202 Net (loss) income attributable to SL Green common stockholders (numerator for diluted earnings per share) $ (7,940) $ 121,003 Three Months Ended March 31, Denominator 2021 2020 Basic Shares: Weighted average common stock outstanding 69,010 75,656 Effect of Dilutive Securities: Operating Partnership units redeemable for common shares 4,148 4,220 Stock-based compensation plans 595 476 Contingently issuable shares from special dividend declared December 4, 2020 and issued January 15, 2021 317 — Diluted weighted average common stock outstanding 74,070 80,352 The Company has excluded 1,159,343 common stock equivalents from the calculation of diluted shares outstanding for the three months ended March 31, 2021, as they were anti-dilutive. The Company has excluded 1,170,579 common stock equivalents from the calculation of diluted shares outstanding for the three months ended March 31, 2020, as they were anti-dilutive. The following tables set forth the changes in accumulated other comprehensive loss by component as of March 31, 2021 (in thousands): Net unrealized loss on derivative instruments ( 1 ) SL Green’s share of joint venture net unrealized loss on derivative instruments ( 2 ) Net unrealized gain (loss) on marketable securities Total Balance at December 31, 2020 $ (57,415) $ (10,853) $ 1,021 $ (67,247) Other comprehensive income before reclassifications 9,771 33,024 (247) 42,548 Amounts reclassified from accumulated other comprehensive loss 4,196 1,606 — 5,802 Balance at March 31, 2021 $ (43,448) $ 23,777 $ 774 $ (18,897) (1) Amount reclassified from accumulated other comprehensive loss is included in interest expense in the respective consolidated statements of operations. As of March 31, 2021 and December 31, 2020, the deferred net gains from these terminated hedges, which is included in accumulated other comprehensive loss relating to net unrealized loss on derivative instrument, was $(0.6) million and $(0.5) million, respectively. (2) Amount reclassified from accumulated other comprehensive loss is included in equity in net loss from unconsolidated joint ventures in the respective consolidated statements of operations.
SL Green Operating Partnership
Stockholders' Equity
Partners' Capital of the Operating Partnership	Partners' Capital of the Operating Partnership The Company is the sole managing general partner of the Operating Partnership and at March 31, 2021 owned 69,353,606 general and limited partnership interests in the Operating Partnership and 9,200,000 Series I Preferred Units. Partnership interests in the Operating Partnership are denominated as “common units of limited partnership interest” (also referred to as “OP Units”) or “preferred units of limited partnership interest” (also referred to as “Preferred Units”). All references to OP Units and Preferred Units outstanding exclude such units held by the Company. A holder of an OP Unit may present such OP Unit to the Operating Partnership for redemption at any time (subject to restrictions agreed upon at the issuance of OP Units to particular holders that may restrict such right for a period of time, generally one year from issuance). Upon presentation of an OP Unit for redemption, the Operating Partnership must redeem such OP Unit in exchange for the cash equal to the then value of a share of common stock of the Company, except that the Company may, at its election, in lieu of cash redemption, acquire such OP Unit for one share of common stock. Because the number of shares of common stock outstanding at all times equals the number of OP Units that the Company owns, one share of common stock is generally the economic equivalent of one OP Unit, and the quarterly distribution that may be paid to the holder of an OP Unit equals the quarterly dividend that may be paid to the holder of a share of common stock. Each series of Preferred Units makes a distribution that is set in accordance with an amendment to the partnership agreement of the Operating Partnership. Preferred Units may also be convertible into OP Units at the election of the holder thereof or the Company, subject to the terms of such Preferred Units. Net income (loss) allocated to the preferred unitholders and common unitholders reflects their pro rata share of net income (loss) and distributions. All unit-related references and measurements including the number of units outstanding and earnings per unit have been retroactively adjusted to reflect the reverse stock split effectuated by SL Green’s board of directors in January 2021 for all periods presented in this Quarterly Report on Form 10-Q. Limited Partner Units As of March 31, 2021, limited partners other than SL Green owned 5.65%, or 4,156,282 common units, of the Operating Partnership. Preferred Units Preferred units not owned by SL Green are further described in Note 11, “Noncontrolling Interests on the Company’s Consolidated Financial Statements - Preferred Units of Limited Partnership Interest in the Operating Partnership.” Earnings per Unit The Operating Partnership's earnings per unit for the three months ended March 31, 2021 and 2020, respectively, are computed as follows (in thousands): Three Months Ended March 31, Numerator 2021 2020 Basic Earnings: Net (loss) income attributable to SLGOP common unitholders $ (7,940) $ 121,003 Less: distributed earnings allocated to participating securities (371) (113) Less: undistributed earnings allocated to participating securities — (464) Net (loss) income attributable to SLGOP common unitholders (numerator for basic earnings per unit) $ (8,311) $ 120,426 Add back: dilutive effect of earnings allocated to participating securities 371 113 Add back: undistributed earnings allocated to participating securities — 464 Net (loss) income attributable to SLGOP common unitholders (numerator for diluted earnings per unit) $ (7,940) $ 121,003 Three Months Ended March 31, Denominator 2021 2020 Basic units: Weighted average common units outstanding 73,158 79,876 Effect of Dilutive Securities: Stock-based compensation plans 595 476 Contingently issuable units from special distribution declared December 4, 2020 and issued January 15, 2021 317 — Diluted weighted average common units outstanding 74,070 80,352 The Operating Partnership has excluded 1,159,343 common unit equivalents from the diluted units outstanding for the three months ended March 31, 2021 as they were anti-dilutive. The Operating Partnership has excluded 1,170,579 common unit equivalents from the diluted units outstanding for the three months ended March 31, 2020 as they were anti-dilutive.

Share-based Compensation

Share-based Compensation	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Share-based Compensation	Share-based CompensationWe have share-based employee and director compensation plans. Our employees are compensated through the Operating Partnership. Under each plan, whenever the Company issues common or preferred stock, the Operating Partnership issues an equivalent number of units of limited partnership interest of a corresponding class to the Company. The Fourth Amended and Restated 2005 Stock Option and Incentive Plan, or the 2005 Plan, was approved by the Company's board of directors in April 2016 and its stockholders in June 2016 at the Company's annual meeting of stockholders. The 2005 Plan authorizes the issuance of stock options, stock appreciation rights, unrestricted and restricted stock, phantom shares, dividend equivalent rights, cash-based awards and other equity-based awards. Subject to adjustments upon certain corporate transactions or events, awards with respect to up to a maximum of 27,030,000 fungible units may be granted under the 2005 Plan. Currently, different types of awards count against the limit on the number of fungible units differently, with (1) full-value awards (i.e., those that deliver the full value of the award upon vesting, such as restricted stock) counting as 3.74 Fungible Units per share subject to such awards, (2) stock options, stock appreciation rights and other awards that do not deliver full value and expire five years from the date of grant counting as 0.73 fungible units per share subject to such awards, and (3) all other awards (e.g., 10-year stock options) counting as 1.0 fungible units per share subject to such awards. Awards granted under the 2005 Plan prior to the approval of the fourth amendment and restatement in June 2016 continue to count against the fungible unit limit based on the ratios that were in effect at the time such awards were granted, which may be different than the current ratios. As a result, depending on the types of awards issued, the 2005 Plan may result in the issuance of more or less than 27,030,000 shares. If a stock option or other award granted under the 2005 Plan expires or terminates, the common stock subject to any portion of the award that expires or terminates without having been exercised or paid, as the case may be, will again become available for the issuance of additional awards. Shares of our common stock distributed under the 2005 Plan may be treasury shares or authorized but unissued shares. Currently, unless the 2005 Plan has been previously terminated by the Company's board of directors, new awards may be granted under the 2005 Plan until June 2, 2026, which is the tenth anniversary of the date that the 2005 Plan was most recently approved by the Company's stockholders. As of March 31, 2021, 1.9 million fungible units were available for issuance under the 2005 Plan after reserving for shares underlying outstanding restricted stock units, phantom stock units granted pursuant to our Non-Employee Directors' Deferral Program and LTIP Units. Stock Options and Class O LTIP Units Options are granted with an exercise price at the fair market value of the Company's common stock on the date of grant and, subject to employment, generally expire five years or ten years from the date of grant, are not transferable other than on death, and generally vest in one year to five years commencing one year from the date of grant. We have also granted Class O LTIP Units, which are a class of LTIP Units in the Operating Partnership structured to provide economics similar to those of stock options. Class O LTIP Units, once vested, may be converted, at the election of the holder, into a number of common units of the Operating Partnership per Class O LTIP Unit determined by the increase in value of a share of the Company’s common stock at the time of conversion over a participation threshold, which equals the fair market value of a share of the Company’s common stock at the time of grant. Class O LTIP Units are entitled to distributions, subject to vesting, equal per unit to 10% of the per unit distributions paid with respect to the common units of the Operating Partnership. The fair value of each stock option or LTIP Unit granted is estimated on the date of grant using the Black-Scholes option pricing model based on historical information. There were no options granted during the three months ended March 31, 2021 or the year ended December 31, 2020. A summary of the status of the Company's stock options as of March 31, 2021 and December 31, 2020, and changes during the three months ended March 31, 2021 and year ended December 31, 2020 are as follows: March 31, 2021 December 31, 2020 Options Outstanding Weighted Average Options Outstanding Weighted Average Balance at beginning of period 784,995 $ 102.62 1,007,665 $ 105.35 Granted — — — — Exercised — — — — Lapsed or canceled (9,716) 86.13 (222,670) 114.97 Balance at end of period 775,279 $ 102.83 784,995 $ 102.62 Options exercisable at end of period 775,278 $ 102.83 782,022 $ 102.62 The remaining weighted average contractual life of the options outstanding was 1.9 years and the remaining average contractual life of the options exercisable was 1.9 years. During the three months ended March 31, 2021, we recognized no compensation expense related to options. During the three months ended March 31, 2020, we recognized compensation expense related to options of $0.02 million. As of March 31, 2021, there was no unrecognized compensation cost related to unvested stock options. Restricted Shares Shares are granted to certain employees, including our executives, and vesting occurs annually upon the completion of a service period or our meeting established financial performance criteria. Annual vesting occurs at rates ranging from 15% to 35% once performance criteria are reached. A summary of the Company's restricted stock as of March 31, 2021 and December 31, 2020 and changes during the three months ended March 31, 2021 and the year ended December 31, 2020, are as follows: March 31, 2021 December 31, 2020 Balance at beginning of period 3,439,674 3,465,347 Granted 145,845 8,959 Canceled (12,437) (34,632) Balance at end of period 3,573,082 3,439,674 Vested during the period 117,487 128,891 Compensation expense recorded $ 2,067,125 $ 10,895,459 Total fair value of restricted stock granted during the period $ 9,214,531 $ 734,315 The fair value of restricted stock that vested during the three months ended March 31, 2021 and the year ended December 31, 2020 was $10.9 million and $12.5 million, respectively. As of March 31, 2021, there was $14.0 million of total unrecognized compensation cost related to restricted stock, which is expected to be recognized over a weighted average period of 2.0 years. We granted LTIP Units, which include bonus, time-based and performance-based awards, with a fair value of $40.3 million and $37.0 million as of March 31, 2021 and December 31, 2020, respectively. The grant date fair value of the LTIP Unit awards was calculated in accordance with ASC 718. A third party consultant determined the fair value of the LTIP Units to have a discount from our common stock price. The discount was calculated by considering the inherent uncertainty that the LTIP Units will reach parity with other common partnership units and the illiquidity due to transfer restrictions. As of March 31, 2021, there was $65.9 million of total unrecognized compensation expense related to the time-based and performance based awards, which is expected to be recognized over a weighted average period of 2.0 years. During the three months ended March 31, 2021, we recorded compensation expense related to bonus, time-based and performance based awards of $9.1 million. During the three months ended March 31, 2020, we recorded compensation expense related to bonus, time-based and performance based awards of $3.0 million. For the three months ended March 31, 2021, $0.5 million was capitalized to assets associated with compensation expense related to our long-term compensation plans, restricted stock and stock options. For the three months ended March 31, 2020, $0.6 million was capitalized to assets associated with compensation expense related to our long-term compensation plans, restricted stock and stock options. Deferred Compensation Plan for Directors Under our Non-Employee Director's Deferral Program, which commenced July 2004, the Company's non-employee directors may elect to defer up to 100% of their annual retainer fee, chairman fees, meeting fees and annual stock grant. Unless otherwise elected by a participant, fees deferred under the program shall be credited in the form of phantom stock units. The program provides that a director's phantom stock units generally will be settled in an equal number of shares of common stock upon the earlier of (i) the January 1 coincident with or the next following such director's termination of service from the Board of Directors or (ii) a change in control by us, as defined by the program. Phantom stock units are credited to each non-employee director quarterly using the closing price of our common stock on the first business day of the respective quarter. Each participating non-employee director is also credited with dividend equivalents or phantom stock units based on the dividend rate for each quarter, which are either paid in cash currently or credited to the director’s account as additional phantom stock units. During the three months ended March 31, 2021, 18,290 phantom stock units and 12,064 shares of common stock were issued to our board of directors. We recorded compensation expense of $1.8 million during the three months ended March 31, 2021 related to the Deferred Compensation Plan. We recorded compensation expense of $1.8 million during the three months ended March 31, 2020 related to the Deferred Compensation Plan. As of March 31, 2021, there were 159,066 phantom stock units outstanding pursuant to our Non-Employee Director's Deferral Program. Employee Stock Purchase Plan

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Accumulated Other Comprehensive Loss	Stockholders’ Equity of the Company Common Stock Our authorized capital stock consists of 260,000,000 shares, $0.01 par value per share, consisting of 160,000,000 shares of common stock, $0.01 par value per share, 75,000,000 shares of excess stock, at $0.01 par value per share, and 25,000,000 shares of preferred stock, par value $0.01 per share. As of March 31, 2021, 69,353,606 shares of common stock and no shares of excess stock were issued and outstanding. On December 4, 2020 our Board of Directors declared an ordinary dividend and a special dividend (together, "the Total Dividend"). The Total Dividend was paid on January 15, 2021 to shareholders of record at the close of business on December 15, 2020 ("the Record Date"). Shareholders had the opportunity to elect to receive the Total Dividend in the form of all cash or all stock, subject to proration if either option was oversubscribed. Shareholders who elected to receive cash received, for each share of common stock they owned as of the Record Date, approximately $0.3735 in cash and 0.0279 shares of common stock. Shareholders who elected to receive shares received, for each share of common stock they owned as of the Record Date, approximately 0.0343 shares of common stock. The number of shares issued was calculated based on the volume weighted average trading price of SLG's common stock between January 5-7, 2021, of $58.15 per share. To mitigate the dilutive impact of the common stock issued in the special dividend, the board of directors also authorized a reverse stock split, which was effective after markets closed on January 20, 2021. On January 8, 2021, a committee of the Board of Directors calculated the ratio for the reverse stock split of our issued and outstanding shares of common stock as 1.02918-for-1. After the issuance of the dividend and the completion of the reverse stock split, the number of shares of our common stock outstanding was equivalent to the number of total shares outstanding on the Record Date (not including any issuances or repurchases that occurred following the Record Date, as well as any fractional shares that would have been issued but for which cash-in-lieu was paid). However, on a relative basis, some individual shareholders may have more shares of SLG’s common stock, and some individual shareholders may have fewer shares of our common stock, depending on their individual elections to receive cash or stock and as a result of the cash option being oversubscribed. All share-related references and measurements including the number of shares outstanding, share prices, number of shares repurchased, earnings per share, dividends per share, and share-based compensation awards, have been retroactively adjusted to reflect the reverse stock split for all periods presented in this Quarterly Report on Form 10-Q. Share Repurchase Program In August 2016, our Board of Directors approved a $1.0 billion share repurchase program under which we can buy shares of our common stock. The Board of Directors has since authorized five separate $500.0 million increases to the size of the share repurchase program in the fourth quarter of 2017, second quarter of 2018, fourth quarter of 2018, fourth quarter of 2019, and fourth quarter of 2020 bringing the total program size to $3.5 billion. At March 31, 2021, share repurchases, excluding the redemption of OP units, executed under the program were as follows: Period Shares repurchased Average price paid per share Cumulative number of shares repurchased as part of the repurchase plan or programs Year ended 2017 8,105,881 $104.61 8,105,881 Year ended 2018 9,468,617 $99.03 17,574,498 Year ended 2019 4,465,857 $86.06 22,040,355 Year Ended 2020 8,529,279 $62.39 30,569,634 Three months ended March 31, 2021 1,306,460 $61.46 31,876,094 Perpetual Preferred Stock We have 9,200,000 shares of our 6.50% Series I Cumulative Redeemable Preferred Stock, or the Series I Preferred Stock, outstanding with a mandatory liquidation preference of $25.00 per share. The Series I Preferred stockholders receive annual dividends of $1.625 per share paid on a quarterly basis and dividends are cumulative, subject to certain provisions. We are entitled to redeem the Series I Preferred Stock at any time, in whole or from time to time in part, at par for cash. In August 2012, we received $221.9 million in net proceeds from the issuance of the Series I Preferred Stock, which were recorded net of underwriters' discount and issuance costs, and contributed the net proceeds to the Operating Partnership in exchange for 9,200,000 units of 6.50% Series I Cumulative Redeemable Preferred Units of limited partnership interest, or the Series I Preferred Units. Dividend Reinvestment and Stock Purchase Plan ("DRSPP") In February 2018, the Company filed a registration statement with the SEC for our dividend reinvestment and stock purchase plan, or DRSPP, which automatically became effective upon filing. The Company registered 3,500,000 shares of our common stock under the DRSPP. The DRSPP commenced on September 24, 2001. The following table summarizes SL Green common stock issued, and proceeds received from dividend reinvestments and/or stock purchases under the DRSPP for the three months ended March 31, 2021 and 2020, respectively (dollars in thousands): Three Months Ended March 31, 2021 2020 Shares of common stock issued 5,483 1,727 Dividend reinvestments/stock purchases under the DRSPP $ 351 $ 166 Earnings per Share We use the two-class method of computing earnings per share (“EPS”), which is an earnings allocation formula that determines EPS for common stock and any participating securities according to dividends declared (whether paid or unpaid). Under the two-class method, basic EPS is computed by dividing the income available to common stockholders by the weighted-average number of common stock shares outstanding for the period. Diluted EPS reflects the potential dilution that could occur from share equivalent activity. SL Green's earnings per share for the three months ended March 31, 2021 and 2020 are computed as follows (in thousands): Three Months Ended March 31, Numerator 2021 2020 Basic Earnings: Net (loss) income attributable to SL Green common stockholders $ (7,464) $ 114,801 Less: distributed earnings allocated to participating securities (371) (113) Less: undistributed earnings allocated to participating securities — (464) Net (loss) income attributable to SL Green common stockholders (numerator for basic earnings per share) $ (7,835) $ 114,224 Add back: dilutive effect of earnings allocated to participating securities 371 113 Add back: undistributed earnings allocated to participating securities — 464 Add back: effect of dilutive securities (redemption of units to common shares) (476) 6,202 Net (loss) income attributable to SL Green common stockholders (numerator for diluted earnings per share) $ (7,940) $ 121,003 Three Months Ended March 31, Denominator 2021 2020 Basic Shares: Weighted average common stock outstanding 69,010 75,656 Effect of Dilutive Securities: Operating Partnership units redeemable for common shares 4,148 4,220 Stock-based compensation plans 595 476 Contingently issuable shares from special dividend declared December 4, 2020 and issued January 15, 2021 317 — Diluted weighted average common stock outstanding 74,070 80,352 The Company has excluded 1,159,343 common stock equivalents from the calculation of diluted shares outstanding for the three months ended March 31, 2021, as they were anti-dilutive. The Company has excluded 1,170,579 common stock equivalents from the calculation of diluted shares outstanding for the three months ended March 31, 2020, as they were anti-dilutive. The following tables set forth the changes in accumulated other comprehensive loss by component as of March 31, 2021 (in thousands): Net unrealized loss on derivative instruments ( 1 ) SL Green’s share of joint venture net unrealized loss on derivative instruments ( 2 ) Net unrealized gain (loss) on marketable securities Total Balance at December 31, 2020 $ (57,415) $ (10,853) $ 1,021 $ (67,247) Other comprehensive income before reclassifications 9,771 33,024 (247) 42,548 Amounts reclassified from accumulated other comprehensive loss 4,196 1,606 — 5,802 Balance at March 31, 2021 $ (43,448) $ 23,777 $ 774 $ (18,897) (1) Amount reclassified from accumulated other comprehensive loss is included in interest expense in the respective consolidated statements of operations. As of March 31, 2021 and December 31, 2020, the deferred net gains from these terminated hedges, which is included in accumulated other comprehensive loss relating to net unrealized loss on derivative instrument, was $(0.6) million and $(0.5) million, respectively. (2) Amount reclassified from accumulated other comprehensive loss is included in equity in net loss from unconsolidated joint ventures in the respective consolidated statements of operations.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value MeasurementsWe are required to disclose fair value information with regard to our financial instruments, whether or not recognized in the consolidated balance sheets, for which it is practical to estimate fair value. The FASB guidance defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants on the measurement date. We measure and/or disclose the estimated fair value of financial assets and liabilities based on a hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity and the reporting entity’s own assumptions about market participant assumptions. This hierarchy consists of three broad levels: Level 1 - quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity can access at the measurement date; Level 2 - inputs other than quoted prices included within Level 1, that are observable for the asset or liability, either directly or indirectly; and Level 3 - unobservable inputs for the asset or liability that are used when little or no market data is available. We follow this hierarchy for our assets and liabilities measured at fair value on a recurring and nonrecurring basis. In instances in which the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level of input that is significant to the fair value measurement in its entirety. Our assessment of the significance of the particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. The following tables set forth the assets and liabilities that we measure at fair value on a recurring and non-recurring basis by their levels in the fair value hierarchy at March 31, 2021 and December 31, 2020 (in thousands): March 31, 2021 Total Level 1 Level 2 Level 3 Assets: Marketable securities $ 23,784 $ — $ 23,784 $ — Interest rate cap and swap agreements (included in Other assets) $ 365 $ — $ 365 $ — Liabilities: Interest rate cap and swap agreements (included in Other liabilities) $ 47,033 $ — $ 47,033 $ — December 31, 2020 Total Level 1 Level 2 Level 3 Assets: Marketable securities $ 28,570 $ — $ 28,570 $ — Interest rate cap and swap agreements (included in Other assets) $ 28 $ — $ 28 $ — Liabilities: Interest rate cap and swap agreements (included in Other liabilities) $ 61,217 $ — $ 61,217 $ — We evaluate real estate investments and debt and preferred equity investments, including intangibles, for potential impairment primarily utilizing cash flow projections that apply, among other things, estimated revenue and expense growth rates, discount rates and capitalization rates, as well as sales comparison approach, which utilizes comparable sales, listings and sales contracts. All of which are classified as Level 3 inputs. In January 2021, pursuant to the partnership documents of our 885 Third Avenue investment, certain participating rights of the common member expired. As a result, it was determined that this investment is a VIE of which we are the primary beneficiary, and the investment was consolidated in our financial statements. Upon consolidating the entity, the assets and liabilities of the entity were recorded at fair value. This fair value was determined using a third party valuation which primarily utilized cash flow projections that apply, among other things, estimated revenue and expense growth rates, discount rates and capitalization rates, as well as sales comparison approach, which utilizes comparable sales, listings and sales contracts. All of which are classified as Level 3 inputs. Marketable securities classified as Level 1 are derived from quoted prices in active markets. The valuation technique used to measure the fair value of marketable securities classified as Level 2 were valued based on quoted market prices or model driven valuations using the significant inputs derived from or corroborated by observable market data. We do not intend to sell these securities and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases. The fair value of derivative instruments is based on current market data received from financial sources that trade such instruments and are based on prevailing market data and derived from third party proprietary models based on well-recognized financial principles and reasonable estimates about relevant future market conditions, which are classified as Level 2 inputs. The financial assets and liabilities that are not measured at fair value on our consolidated balance sheets include cash and cash equivalents, restricted cash, accounts receivable, accounts payable and accrued expenses, debt and preferred equity investments, mortgages and other loans payable and other secured and unsecured debt. The carrying amount of cash and cash equivalents, restricted cash, accounts receivable, and accounts payable and accrued expenses reported in our consolidated balance sheets approximates fair value due to the short-term nature of these instruments. The fair value of debt and preferred equity investments, which is classified as Level 3, is estimated by discounting the future cash flows using current interest rates at which similar loans with the same maturities would be made to borrowers with similar credit ratings. The fair value of borrowings, which is classified as Level 3, is estimated by discounting the contractual cash flows of each debt instrument to their present value using adjusted market interest rates, which is provided by a third-party specialist. The following table provides the carrying value and fair value of these financial instruments as of March 31, 2021 and December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Carrying Value (1) Fair Value Carrying Value (1) Fair Value Debt and preferred equity investments $ 1,097,202 (2) $ 1,076,542 (2) Fixed rate debt $ 3,932,789 $ 4,027,789 $ 3,135,572 $ 3,237,075 Variable rate debt 1,416,521 1,420,814 1,827,677 1,822,740 $ 5,349,310 $ 5,448,603 $ 4,963,249 $ 5,059,815 (1) Amounts exclude net deferred financing costs. (2) At March 31, 2021, debt and preferred equity investments had an estimated fair value ranging between $1.0 billion and $1.1 billion. At December 31, 2020, debt and preferred equity investments had an estimated fair value ranging between $1.0 billion and $1.1 billion. Disclosure about fair value of financial instruments was based on pertinent information available to us as of March 31, 2021 and December 31, 2020. Such amounts have not been comprehensively revalued for purposes of these financial statements since that date and current estimates of fair value may differ significantly from the amounts presented herein.

Financial Instruments_ Derivati

Financial Instruments: Derivatives and Hedging	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments: Derivatives and Hedging	Financial Instruments: Derivatives and Hedging In the normal course of business, we use a variety of commonly used derivative instruments, such as interest rate swaps, caps, collar and floors, to manage, or hedge interest rate risk. We hedge our exposure to variability in future cash flows for forecasted transactions in addition to anticipated future interest payments on existing debt. We recognize all derivatives on the balance sheet at fair value. Derivatives that are not hedges are adjusted to fair value through earnings. If a derivative is a hedge, depending on the nature of the hedge, changes in the fair value of the derivative will either be offset against the change in fair value of the hedge asset, liability, or firm commitment through earnings, or recognized in other comprehensive income (loss) until the hedged item is recognized in earnings. Reported net income and equity may increase or decrease prospectively, depending on future levels of interest rates and other variables affecting the fair values of derivative instruments and hedged items, but will have no effect on cash flows. Currently, all of our designated derivative instruments are effective hedging instruments. The following table summarizes the notional value at inception and fair value of our consolidated derivative financial instruments at March 31, 2021 based on Level 2 information. The notional value is an indication of the extent of our involvement in these instruments at that time, but does not represent exposure to credit, interest rate or market risks (dollars in thousands). Notional Strike Effective Expiration Balance Sheet Location Fair Interest Rate Swap $ 350,000 0.544 % April 2020 August 2021 Other Liabilities $ (472) Interest Rate Cap 111,869 3.500 % December 2020 November 2021 Other Assets — Interest Rate Cap 510,000 3.000 % June 2020 December 2021 Other Assets — Interest Rate Swap 200,000 0.138 % February 2021 February 2022 Other Liabilities (3) Interest Rate Swap 100,000 0.136 % February 2021 February 2022 Other Assets — Interest Rate Cap 85,000 4.000 % March 2021 March 2022 Other Assets — Interest Rate Swap 100,000 0.212 % January 2021 January 2023 Other Assets 95 Interest Rate Swap 400,000 0.160 % February 2021 February 2023 Other Assets 270 Interest Rate Swap 200,000 1.131 % July 2016 July 2023 Other Liabilities (4,017) Interest Rate Swap 100,000 1.161 % July 2016 July 2023 Other Liabilities (2,077) Interest Rate Swap 150,000 2.696 % January 2019 January 2024 Other Liabilities (9,675) Interest Rate Swap 150,000 2.721 % January 2019 January 2026 Other Liabilities (13,117) Interest Rate Swap 200,000 2.740 % January 2019 January 2026 Other Liabilities (17,672) $ (46,668) No gains or losses on the changes in the fair values were included in interest expense in the consolidated statements of operations during the three months ended March 31, 2021 or 2020. The Company has agreements with each of its derivative counterparties that contain a provision where if the Company defaults on any of its indebtedness, then the Company could also be declared in default on its derivative obligations. As of March 31, 2021, the fair value of derivatives in a net liability position, including accrued interest but excluding any adjustment for nonperformance risk related to these agreements, was $48.3 million. As of March 31, 2021, the Company had not posted any collateral related to these agreements and was not in breach of any agreement provisions. If the Company had breached any of these provisions, it could have been required to settle its obligations under the agreements at their aggregate termination value of $49.0 million at March 31, 2021. Gains and losses on terminated hedges are included in accumulated other comprehensive income (loss), and are recognized into earnings over the term of the related mortgage obligation. Over time, the realized and unrealized gains and losses held in accumulated other comprehensive loss will be reclassified into earnings as an adjustment to interest expense in the same periods in which the hedged interest payments affect earnings. We estimate that $16.6 million of the current balance held in accumulated other comprehensive loss will be reclassified into interest expense and $2.2 million of the portion related to our share of joint venture accumulated other comprehensive loss will be reclassified into equity in net loss from unconsolidated joint ventures within the next 12 months. The following table presents the effect of our derivative financial instruments and our share of our joint ventures' derivative financial instruments that are designated and qualify as hedging instruments on the consolidated statements of operations for the three months ended March 31, 2021 and 2020, respectively (in thousands): Amount of Gain (Loss) Location of Loss Reclassified from Accumulated Other Comprehensive Loss into Income Amount of Loss Reclassified from Three Months Ended March 31, Three Months Ended March 31, Derivative 2021 2020 2021 2020 Interest Rate Swaps/Caps $ 10,220 $ (45,082) Interest expense $ (4,388) $ (725) Share of unconsolidated joint ventures' derivative instruments 34,955 (7,089) Equity in net loss from unconsolidated joint ventures (1,700) (711) $ 45,175 $ (52,171) $ (6,088) $ (1,436) The following table summarizes the notional value at inception and fair value of our joint ventures' derivative financial instruments at March 31, 2021 based on Level 2 information. The notional value is an indication of the extent of our involvement in these instruments at that time, but does not represent exposure to credit, interest rate or market risks (dollars in thousands). Notional Strike Effective Expiration Classification Fair Interest Rate Swap $ 177,000 1.669 % March 2016 February 2026 Liability $ (6,459) Interest Rate Cap 375,000 2.600 % August 2018 September 2021 Asset — Interest Rate Cap 20,026 2.600 % April 2019 September 2021 Asset — Interest Rate Cap 198,000 4.000 % August 2019 August 2022 Asset 2 Interest Rate Cap 220,000 4.000 % February 2020 February 2022 Asset — Interest Rate Cap 550,000 3.750 % August 2020 September 2023 Asset 138 Interest Rate Cap 1,075,000 3.750 % September 2020 September 2021 Asset — Interest Rate Cap 125,000 3.750 % September 2020 September 2021 Asset — Interest Rate Cap 1,250,000 1.250 % November 2020 October 2024 Asset 5,764 Interest Rate Cap 23,000 4.750 % January 2021 January 2023 Asset 1 Interest Rate Swap 2,250,000 1.611 % June 2021 June 2031 Asset 42,635 $ 42,081

Lease Income

Lease Income	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Lease Income	Lease Income The Operating Partnership is the lessor and the sublessor to tenants under operating and sales-type leases. The minimum rental amounts due under the leases are generally subject to scheduled fixed increases or adjustments. The leases generally also require that the tenants reimburse us for increases in certain operating costs and real estate taxes above their base year costs. The components of lease income from operating leases during the quarters ended March 31, 2021 and 2020 were as follows (in thousands): Three Months Ended March 31, 2021 2020 Fixed lease payments $ 164,679 $ 194,224 Variable lease payments 25,279 27,168 Total lease payments (1) $ 189,958 $ 221,392 Amortization of acquired above and below-market leases (1,869) 1,239 Total rental revenue $ 188,089 $ 222,631 (1) Amounts include $65.8 million and $66.3 million of sublease income during the three months ended March 31, 2021 and 2020, respectively. The components of lease income from sales-type leases during the quarters ended March 31, 2021 and 2020 were as follows (in thousands): Three Months Ended March 31, 2021 2020 Interest income (1) $ 1,101 $ — (1) These amounts are included in Other income in our consolidated statements of operations.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings As of March 31, 2021, the Company and the Operating Partnership were not involved in any material litigation nor, to management's knowledge, was any material litigation threatened against us or our portfolio which if adversely determined could have a material adverse impact on us. Environmental Matters Our management believes that the properties are in compliance in all material respects with applicable Federal, state and local ordinances and regulations regarding environmental issues. Management is not aware of any environmental liability that it believes would have a materially adverse impact on our financial position, results of operations or cash flows. Management is unaware of any instances in which it would incur significant environmental cost if any of our properties were sold. Lease Arrangements We are a tenant under leases for certain properties, including ground leases. These leases have expirations from 2022 to 2119, or 2043 to 2119 as fully extended. Certain leases offer extension options which we assess against relevant economic factors to determine whether we are reasonably certain of exercising or not exercising the option. Lease payments associated with renewal periods that we are reasonably certain will be exercised, if any, are included in the measurement of the corresponding lease liability and right of use asset. Certain of our leases are subject to rent resets, generally based on a percentage of the then fair market value, a fixed amount, or a percentage of the preceding rent at specified future dates. Rent resets will be recognized in the periods in which they are incurred. The table below summarizes our current lease arrangements as of March 31, 2021: Property (1) Year of Current Expiration Year of Final Expiration (2) 1185 Avenue of the Americas 2043 2043 SL Green Headquarters at One Vanderbilt (3) 2043 2048 625 Madison Avenue 2022 2054 420 Lexington Avenue 2050 2080 885 Third Avenue 2080 2080 711 Third Avenue (4) 2033 2083 461 Fifth Avenue (5) 2027 2084 1080 Amsterdam Avenue (6) 2111 2111 15 Beekman (7)(8) 2119 2119 (1) All leases are classified as operating leases unless otherwise specified. (2) Reflects exercise of all available extension options. (3) In March 2021, the Company's lease for its corporate headquarters at One Vanderbilt commenced. See note 10, "Related Party Transactions." (4) The Company owns 50% of the fee interest. (5) In April 2021, the Company exercised its option to acquire the fee interest in the property. The transaction is expected to close in the second quarter of 2021 . The lease is classified as a financing lease. (6) A portion of the lease is classified as a financing lease. (7) The Company has an option to purchase the ground lease for a fixed price on a specific date. The lease is classified as a financing lease. (8) In August 2020, the Company entered into a long-term sublease with an unconsolidated joint venture as part of the capitalization of the 15 Beekman development project. See Note 6, "Investments in Unconsolidated Joint Ventures." The following is a schedule of future minimum lease payments as evaluated in accordance with ASC 842 for our financing leases and operating leases with initial terms in excess of one year as of March 31, 2021 (in thousands): Financing leases Operating leases Remaining 2021 $ 31,136 $ 31,954 2022 3,522 29,386 2023 3,570 29,502 2024 3,641 30,545 2025 3,810 30,772 2026 3,858 30,911 Thereafter 256,692 631,532 Total minimum lease payments $ 306,229 $ 814,602 Amount representing interest (153,607) Amount discounted using incremental borrowing rate (359,217) Lease liabilities $ 152,622 $ 455,385 The following table provides lease cost information for the Company's operating leases for the three months ended March 31, 2021 or 2020 (in thousands): Three Months Ended March 31, Operating Lease Costs 2021 2020 Operating lease costs before capitalized operating lease costs $ 7,567 $ 8,113 Operating lease costs capitalized (828) (746) Operating lease costs, net (1) $ 6,739 $ 7,367 (1) This amount is included in operating lease rent in our consolidated statements of operations. The following table provides lease cost information for the Company's financing leases for the three months ended March 31, 2021 or 2020 (in thousands): Three Months Ended March 31, Financing Lease Costs 2021 2020 Interest on financing leases before capitalized interest $ 1,492 $ 1,663 Interest on financing leases capitalized — (747) Interest on financing leases, net (1) 1,492 916 Amortization of right-of-use assets (2) 180 305 Financing lease costs, net $ 1,672 $ 1,221 (1) These amounts are included in interest expense, net of interest income in our consolidated statements of operations. (2) These amounts are included in depreciation and amortization in our consolidated statements of operations. As of March 31, 2021, the weighted-average discount rate used to calculate the lease liabilities was 4.52%. As of March 31, 2021, the weighted-average remaining lease term was 27 years, inclusive of purchase options expected to be exercised.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Segment Information	Segment Information The Company has two reportable segments, real estate and debt and preferred equity investments. We evaluate real estate performance and allocate resources based on earnings contributions. The primary sources of revenue are generated from tenant rents and escalations and reimbursement revenue. Real estate property operating expenses consist primarily of security, maintenance, utility costs, insurance, real estate taxes and ground rent expense (at certain applicable properties). See Note 5, "Debt and Preferred Equity Investments," for additional details on our debt and preferred equity investments. Selected consolidated results of operations for the three months ended March 31, 2021 and 2020, and selected asset information as of March 31, 2021 and December 31, 2020, regarding our operating segments are as follows (in thousands): Real Estate Segment Debt and Preferred Equity Segment Total Company Total revenues Three months ended: March 31, 2021 $ 206,829 $ 19,273 $ 226,102 March 31, 2020 275,770 38,533 314,303 Net (loss) income Three months ended: March 31, 2021 $ (20,027) $ 16,172 $ (3,855) March 31, 2020 111,233 15,881 127,114 Total assets As of: March 31, 2021 $ 10,896,203 $ 1,147,842 $ 12,044,045 December 31, 2020 10,579,899 1,127,668 11,707,567 Interest costs for the debt and preferred equity segment include actual costs incurred for borrowings on the 2017 MRA and the FHLB Facility. Interest is imputed on the investments that do not collateralize the 2017 MRA and the FHLB Facility using our weighted average corporate borrowing cost. We also allocate loan loss reserves, net of recoveries, and transaction related costs to the debt and preferred equity segment. We do not allocate marketing, general and administrative expenses to the debt and preferred equity segment because the use of personnel and resources is dependent on transaction volume between the two segments and varies between periods. In addition, we base performance on the individual segments prior to allocating marketing, general and administrative expenses. For the three months ended March 31, 2021, marketing, general and administrative expenses totaled $22.9 million. For the three months ended March 31, 2020, marketing, general and administrative expenses totaled $19.6 million. All other expenses, except interest, relate entirely to the real estate assets. There were no transactions between the above two segments.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include our accounts and those of our subsidiaries, which are wholly-owned or controlled by us. Entities which we do not control through our voting interest and entities which are variable interest entities, but where we are not the primary beneficiary, are accounted for under the equity method. See Note 5, "Debt and Preferred Equity Investments" and Note 6, "Investments in Unconsolidated Joint Ventures." All significant intercompany balances and transactions have been eliminated. We consolidate a VIE in which we are considered the primary beneficiary. The primary beneficiary is the entity that has (i) the power to direct the activities that most significantly impact the entity's economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could be significant to the VIE.
Investment in Commercial Real Estate Properties	Investment in Commercial Real Estate Properties We allocate the purchase price of real estate to land and building (inclusive of tenant improvements) and, if determined to be material, intangibles, such as the value of above- and below-market leases and origination costs associated with the in-place leases. We depreciate the amount allocated to building (inclusive of tenant improvements) over their estimated useful lives, which generally range from 3 years to 40 years. We amortize the amount allocated to the above- and below-market leases over the remaining term of the associated lease, which generally range from 1 year to 15 years, and record it as either an increase (in the case of below-market leases) or a decrease (in the case of above-market leases) to rental income. We amortize the amount allocated to the values associated with in-place leases over the expected term of the associated lease, which generally ranges from 1 year to 15 years. If a tenant vacates its space prior to the contractual termination of the lease and no rental payments are being made on the lease, any unamortized balance of the related intangible will be written off. The tenant improvements and origination costs are amortized as an expense over the remaining life of the lease (or charged against earnings if the lease is terminated prior to its contractual expiration date). We assess fair value of the leases based on estimated cash flow projections that utilize appropriate discount rates and available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known trends, and market/economic conditions that may affect the property. To the extent acquired leases contain fixed rate renewal options that are below-market and determined to be material, we amortize such below-market lease value into rental income over the renewal period. The Company classifies those leases under which the Company is the lessee at lease commencement as finance or operating leases. Leases qualify as finance leases if the lease transfers ownership of the asset at the end of the lease term, the lease grants an option to purchase the asset that we are reasonably certain to exercise, the lease term is for a major part of the remaining economic life of the asset, or the present value of the lease payments exceeds substantially all of the fair value of the asset. Leases that do not qualify as finance leases are deemed to be operating leases. At lease commencement the Company records a lease liability which is measured as the present value of the lease payments and a right of use asset which is measured as the amount of the lease liability and any initial direct costs incurred. The Company applies a discount rate to determine the present value of the lease payments. If the rate implicit in the lease is known, the Company uses that rate. If the rate implicit in the lease is not known, the Company uses a discount rate reflective of the Company’s collateralized borrowing rate given the term of the lease. To determine the discount rate, the Company employs a third party specialist to develop an analysis based primarily on the observable borrowing rates of the Company, other REITs, and other corporate borrowers with long-term borrowings. On the consolidated statements of operations, operating leases are expensed through operating lease rent while financing leases are expensed through amortization and interest expense. On the consolidated balance sheets, financing leases include the amounts previously captioned "Properties under capital lease." When applicable, the Company combines the consideration for lease and non-lease components in the calculation of the value of the lease obligation and right-of-use asset. On a periodic basis, we assess whether there are any indications that the value of our real estate properties may be impaired or that their carrying value may not be recoverable. A property's value is considered impaired if management's estimate of the aggregate future cash flows (undiscounted) to be generated by the property is less than the carrying value of the property. To the extent impairment has occurred, the loss will be measured as the excess of the carrying amount of the property over the fair value of the property as calculated in accordance with Accounting Standards Codification, or ASC 820. We also
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments with maturity of three months or less when purchased to be cash equivalents.
Restricted Cash	Restricted Cash Restricted cash primarily consists of security deposits held on behalf of our tenants, interest reserves, as well as capital improvement and real estate tax escrows required under certain loan agreements.
Investment in Marketable Securities	Investment in Marketable Securities At acquisition, we designate a security as held-to-maturity, available-for-sale, or trading. As of March 31, 2021, we did not have any securities designated as held-to-maturity or trading. We account for our available-for-sale securities at fair value pursuant to ASC 820-10, with the net unrealized gains or losses reported as a component of accumulated other comprehensive income or loss. The cost of marketable securities sold and the amount reclassified out of accumulated other comprehensive income into earnings is determined using the specific identification method. Credit losses are recognized in accordance with ASC 326.
Investments in Unconsolidated Joint Ventures	Investments in Unconsolidated Joint VenturesWe assess our investments in unconsolidated joint ventures for recoverability and if it is determined that a loss in value of the investment is other than temporary, we write down the investment to its fair value. We evaluate our equity investments for impairment based on each joint ventures' actual and projected cash flows.
Deferred Lease Costs and Lease Classification	Deferred Lease Costs Deferred lease costs consist of incremental fees and direct costs that would not have been incurred if the lease had not been obtained and are amortized on a straight-line basis over the related lease term. Lease Classification Lease classification for leases under which the Company is the lessor is evaluated at lease commencement and leases not classified as sales-type leases or direct financing leases are classified as operating leases. Leases qualify as sales-type leases if the contract includes either transfer of ownership clauses, certain purchase options, a lease term representing a major part of the economic life of the asset, or the present value of the lease payments and residual guarantees provided by the lessee exceeds substantially all of the fair value of the asset. Additionally, leasing an asset so specialized that it is not deemed to have any value to the Company at the end of the lease term may also result in classification as a sales-type lease. Leases qualify as direct financing leases when the present value of the lease payments and residual value guarantees provided by the lessee and unrelated third parties exceeds substantially all of the fair value of the asset and collection of the payments is probable.
Revenue Recognition	Revenue Recognition Rental revenue for operating leases is recognized on a straight-line basis over the term of the lease. Rental revenue recognition commences when the leased space is available for its intended use by the lessee. To determine whether the leased space is available for its intended use by the lessee, management evaluates whether we are the owner of tenant improvements for accounting purposes or if the tenant is. When management concludes that we are the owner of tenant improvements, rental revenue recognition begins when the tenant takes possession of the finished space, which is when such tenant improvements are substantially complete. In certain instances, when management concludes that we are not the owner of tenant improvements, rental revenue recognition begins when the tenant takes possession of or controls the space. When management concludes that we are the owner of tenant improvements for accounting purposes, we record amounts funded to construct the tenant improvements as a capital asset. For these tenant improvements, we record amounts reimbursed by tenants as a reduction of the capital asset. When management concludes that the tenant is the owner of tenant improvements for accounting purposes, we record our contribution towards those improvements as a lease incentive, which is included in deferred costs, net on our consolidated balance sheets and amortized as a reduction to rental revenue on a straight-line basis over the term of the lease. The excess of rents recognized over amounts contractually due pursuant to the underlying leases are included in deferred rents receivable on the consolidated balance sheets. In addition to base rent, our tenants also generally will pay variable rent which represents their pro rata share of increases in real estate taxes and certain operating expenses for the building over a base year. In some leases, in lieu of paying additional rent based upon increases in certain building operating expenses, the tenant will pay additional rent based upon increases in the wage rate paid to porters over the porters' wage rate in effect during a base year or increases in the consumer price index over the index value in effect during a base year. In addition, many of our leases contain fixed percentage increases over the base rent to cover escalations. Electricity is most often supplied by the landlord either on a sub-metered basis, or rent inclusion basis (i.e., a fixed fee is included in the rent for electricity, which amount may increase based upon increases in electricity rates or increases in electrical usage by the tenant). Base building services other than electricity (such as heat, air conditioning and freight elevator service during business hours, and base building cleaning) are typically provided at no additional cost, with the tenant paying additional rent only for services which exceed base building services or for services which are provided outside normal business hours. These escalations are based on actual expenses incurred in the prior calendar year. If the expenses in the current year are different from those in the prior year, then during the current year, the escalations will be adjusted to reflect the actual expenses for the current year. Rental revenue is recognized if collectability is probable. If collectability of substantially all of the lease payments is assessed as not probable, any difference between the rental revenue recognized to date and the lease payments that have been collected is recognized as a current-period adjustment to rental revenue. A subsequent change in the assessment of collectability to probable may result in a current-period adjustment to rental revenue for any difference between the rental revenue that would have been recognized if collectability had always been assessed as probable and the rental revenue recognized to date. We recognize lease concessions related to COVID-19, such as rent deferrals and abatements, in accordance with the Lease Modification Q&A issued by the FASB in April 2020, which provides entities with the option to elect to account for lease concessions as though the enforceable rights and obligations existed in the original lease. This election is only available when total cash flows resulting from the modified lease are substantially similar to the cash flows in the original lease. When total cash flows resulting from the modified lease are not substantially similar to the cash flows in the original lease, we account for the concession agreement as a new lease. The Company provides its tenants with certain customary services for lease contracts such as common area maintenance and general security. We have elected to combine the non-lease components with the lease components of our operating lease agreements and account for them as a single lease component in accordance with ASC 842. We record a gain or loss on sale of real estate assets when we no longer have a controlling financial interest in the entity owning the real estate, a contract exists with a third party and that third party has control of the assets acquired. Investment income on debt and preferred equity investments is accrued based on the contractual terms of the instruments and when it is deemed collectible. Some debt and preferred equity investments provide for accrual of interest at specified rates, which differ from current payment terms. Interest is recognized on such loans at the accrual rate subject to management's determination that accrued interest is collectible. If management cannot make this determination, interest income above the current pay rate is recognized only upon actual receipt. Deferred origination fees, original issue discounts and loan origination costs, if any, are recognized as an adjustment to interest income over the terms of the related investments using the effective interest method. Fees received in connection with loan commitments are also deferred until the loan is funded and are then recognized over the term of the loan as an adjustment to yield. Discounts or premiums associated with the purchase of loans are amortized or accreted into interest income as a yield adjustment on the effective interest method based on expected cash flows through the expected maturity date of the related investment. If we purchase a debt or preferred equity investment at a discount, intend to hold it until maturity and expect to recover the full value of the investment, we accrete the discount into income as an adjustment to yield over the term of the investment. If we purchase a debt or preferred equity investment at a discount with the intention of foreclosing on the collateral, we do not accrete the discount. For debt investments acquired at a discount for credit quality, the difference between contractual cash flows and expected cash flows at acquisition is not accreted. Anticipated exit fees, the collection of which is expected, are also recognized over the term of the loan as an adjustment to yield. We consider a debt and preferred equity investment to be past due when amounts contractually due have not been paid. Debt and preferred equity investments are placed on a non-accrual status at the earlier of the date at which payments become 90 days past due or when, in the opinion of management, a full recovery of interest income becomes doubtful. Interest income recognition is resumed on any debt or preferred equity investment that is on non-accrual status when such debt or preferred equity investment becomes contractually current and performance is demonstrated to be resumed. We may syndicate a portion of the loans that we originate or sell the loans individually. When a transaction meets the criteria for sale accounting, we recognize gain or loss based on the difference between the sales price and the carrying value of the loan sold. Any related unamortized deferred origination fees, original issue discounts, loan origination costs, discounts or premiums at the time of sale are recognized as an adjustment to the gain or loss on sale, which is included in investment income on the consolidated statement of operations. Any fees received at the time of sale or syndication are recognized as part of investment income. Asset management fees are recognized on a straight-line basis over the term of the asset management agreement.
Debt and Preferred Equity Investments	Debt and Preferred Equity Investments Debt and preferred equity investments are presented at the net amount expected to be collected in accordance with ASC 326. An allowance for loan losses is deducted from the amortized cost basis of the financial assets to present the net carrying value at the amount expected to be collected through the expected maturity date of such investments. The expense for loan loss and other investment reserves is the charge to earnings to adjust the allowance for loan losses to the appropriate level. Amounts are written off from the allowance when we de-recognize the related investment either as a result of a sale of the investment or acquisition of equity interests in the collateral. The Company evaluates the amount expected to be collected based on current market and economic conditions, historical loss information, and reasonable and supportable forecasts. The Company's assumptions are derived from both internal data and external data which may include, among others, governmental economic projections for the New York City Metropolitan area, public data on recent transactions and filings for securitized debt instruments. This information is aggregated by asset class and adjusted for duration. Based on these inputs, loans are evaluated at the individual asset level. In certain instances, we may also use a probability-weighted model that considers the likelihood of multiple outcomes and the amount expected to be collected for each outcome. The evaluation of the possible credit deterioration associated with the performance and/or value of the underlying collateral property as well as the financial and operating capability of the borrower/sponsor requires significant judgment, which include both asset level and market assumptions over the relevant time period. In addition, quarterly, the Company assigns each loan a risk rating. Based on a 3-point scale, loans are rated “1” through “3,” from lower risk to higher risk, which ratings are defined as follows: 1 - Low Risk Assets - Low probability of loss, 2 - Watch List Assets - Higher potential for loss, 3 - High Risk Assets - Loss more likely than not. Loans with risk ratings of 2 or above are evaluated to determine whether the expected risk of loss is appropriately captured through the combination of our expectations of current conditions, historical loss information and supportable forecasts described above or whether risk characteristics specific to the loan warrant the use of a probability-weighted model. Financing investments that are classified as held for sale are carried at the expected amount to be collected or fair market value using available market information obtained through consultation with dealers or other originators of such investments as well as discounted cash flow models based on Level 3 data pursuant to ASC 820-10. As circumstances change, management may conclude not to sell an investment designated as held for sale. In such situations, the investment will be reclassified at its expected amount to be collected. Other financing receivables that are included in balance sheet line items other than the Debt and Preferred Equity Investments line are also measured at the net amount expected to be collected. Accrued interest receivable amounts related to these debt and preferred equity investment and other financing receivables are recorded at the net amount expected to be collected within Other assets in the consolidated balance sheets. Accrued interest receivables that are written off are recognized as an expense in loan loss and other investment reserves.
Income Taxes	Income Taxes SL Green is taxed as a REIT under Section 856(c) of the Code. As a REIT, SL Green generally is not subject to Federal income tax. To maintain its qualification as a REIT, SL Green must distribute at least 90% of its REIT taxable income to its stockholders and meet certain other requirements. If SL Green fails to qualify as a REIT in any taxable year, SL Green will be subject to Federal income tax on its taxable income at regular corporate rates. SL Green may also be subject to certain state, local and franchise taxes. Under certain circumstances, Federal income and excise taxes may be due on its undistributed taxable income. The Operating Partnership is a partnership and, as a result, all income and losses of the partnership are allocated to the partners for inclusion in their respective income tax returns. The only provision for income taxes included in the consolidated statements of operations relates to the Operating Partnership’s consolidated taxable REIT subsidiaries. The Operating Partnership may also be subject to certain state, local and franchise taxes. We have elected, and may elect in the future, to treat certain of our corporate subsidiaries as taxable REIT subsidiaries, or TRSs. In general, TRSs may perform non-customary services for the tenants of the Company, hold assets that we cannot hold directly and generally may engage in any real estate or non-real estate related business. The TRSs generate income, resulting in Federal and state income tax liability for these entities. During the three months ended March 31, 2021, we recorded a Federal, state and local tax provision of $0.7 million. During the three months ended March 31, 2020, we recorded a Federal, state and local provision of $1.1 million. We follow a two-step approach for evaluating uncertain tax positions. Recognition (step one) occurs when an enterprise concludes that a tax position, based solely on its technical merits, is more-likely-than-not to be sustained upon examination. Measurement (step two) determines the amount of benefit that is more-likely-than-not to be realized upon settlement. Derecognition of a tax position that was previously recognized would occur when a company subsequently determines that a tax position no longer meets the more-likely-than-not threshold of being sustained. The use of a valuation allowance as a substitute for derecognition of tax positions is prohibited.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash investments, debt and preferred equity investments and accounts receivable. We place our cash investments with high quality financial institutions. The collateral securing our debt and preferred equity investments is located in New York City. See Note 5, "Debt and Preferred Equity Investments."
Reclassification	Reclassification Certain prior year balances have been reclassified to conform to our current year presentation.
Accounting Standards Updates	Accounting Standards Updates In August 2020, the FASB issued Accounting Standard Update, or "ASU," No. 2020-06 Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40). ASU 2020-06 simplifies the accounting for convertible instruments by reducing the number of accounting models for convertible debt instruments and convertible preferred stock, removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and also simplifies the diluted earnings per share calculation in certain areas. ASU 2020-06 is effective for reporting periods beginning after December 15, 2021, with early adoption permitted. We are currently evaluating the impact of the adoption of ASU 2020-06 on our consolidated financial statements, but do not believe the adoption of this standard will have a material impact on our consolidated financial statements. In March 2020, the FASB issued ASU No. 2020-04 Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting and then in January 2021, the FASB issued ASU No. 2021-01. The amendments provide practical expedients for reference rate reform related activities that impact debt, leases, derivatives and other contracts. The guidance is optional and is effective between March 12, 2020 and December 31, 2022. The guidance may be elected over time as reference rate reform activities occur. During the first quarter of 2020, the Company elected to apply the hedge accounting expedients related to probability and the assessments of effectiveness for future LIBOR-indexed cash flows to assume that the index upon which future hedged transactions will be based matches the index on the corresponding derivatives. Application of these expedients preserves the presentation of derivatives consistent with past presentation. The Company continues to evaluate the impact of the guidance and may apply other elections as applicable as additional changes in the market occur.
Fair Value Measurements	Fair Value MeasurementsWe are required to disclose fair value information with regard to our financial instruments, whether or not recognized in the consolidated balance sheets, for which it is practical to estimate fair value. The FASB guidance defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants on the measurement date. We measure and/or disclose the estimated fair value of financial assets and liabilities based on a hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity and the reporting entity’s own assumptions about market participant assumptions. This hierarchy consists of three broad levels: Level 1 - quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity can access at the measurement date; Level 2 - inputs other than quoted prices included within Level 1, that are observable for the asset or liability, either directly or indirectly; and Level 3 - unobservable inputs for the asset or liability that are used when little or no market data is available. We follow this hierarchy for our assets and liabilities measured at fair value on a recurring and nonrecurring basis. In instances in which the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level of input that is significant to the fair value measurement in its entirety. Our assessment of the significance of the particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. We evaluate real estate investments and debt and preferred equity investments, including intangibles, for potential impairment primarily utilizing cash flow projections that apply, among other things, estimated revenue and expense growth rates, discount rates and capitalization rates, as well as sales comparison approach, which utilizes comparable sales, listings and sales contracts. All of which are classified as Level 3 inputs. In January 2021, pursuant to the partnership documents of our 885 Third Avenue investment, certain participating rights of the common member expired. As a result, it was determined that this investment is a VIE of which we are the primary beneficiary, and the investment was consolidated in our financial statements. Upon consolidating the entity, the assets and liabilities of the entity were recorded at fair value. This fair value was determined using a third party valuation which primarily utilized cash flow projections that apply, among other things, estimated revenue and expense growth rates, discount rates and capitalization rates, as well as sales comparison approach, which utilizes comparable sales, listings and sales contracts. All of which are classified as Level 3 inputs. Marketable securities classified as Level 1 are derived from quoted prices in active markets. The valuation technique used to measure the fair value of marketable securities classified as Level 2 were valued based on quoted market prices or model driven valuations using the significant inputs derived from or corroborated by observable market data. We do not intend to sell these securities and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases. The fair value of derivative instruments is based on current market data received from financial sources that trade such instruments and are based on prevailing market data and derived from third party proprietary models based on well-recognized financial principles and reasonable estimates about relevant future market conditions, which are classified as Level 2 inputs. The financial assets and liabilities that are not measured at fair value on our consolidated balance sheets include cash and cash equivalents, restricted cash, accounts receivable, accounts payable and accrued expenses, debt and preferred equity investments, mortgages and other loans payable and other secured and unsecured debt. The carrying amount of cash and cash equivalents, restricted cash, accounts receivable, and accounts payable and accrued expenses reported in our consolidated balance sheets approximates fair value due to the short-term nature of these instruments. The fair value of debt and preferred equity investments, which is classified as Level 3, is estimated by discounting the future cash flows using current interest rates at which similar loans with the same maturities would be made to borrowers with similar credit ratings. The fair value of borrowings, which is classified as Level 3, is estimated by discounting the contractual cash flows of each debt instrument to their present value using adjusted market interest rates, which is provided by a third-party specialist.

Organization and Basis of Pre_2

Organization and Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of commercial office properties	As of March 31, 2021, we owned the following interests in properties in the New York metropolitan area, primarily in midtown Manhattan. Our investments located outside of Manhattan are referred to as the Suburban properties: Consolidated Unconsolidated Total Location Property Number of Buildings Approximate Square Feet (unaudited) Number of Buildings Approximate Square Feet (unaudited) Number of Buildings Approximate Square Feet (unaudited) Weighted Average Occupancy (1) (unaudited) Commercial: Manhattan Office 18 10,526,345 9 10,869,183 27 21,395,528 93.4 % Retail 1 10,040 9 301,996 10 312,036 94.6 % Development/Redevelopment 9 1,890,614 3 2,927,782 12 4,818,396 N/A 28 12,426,999 21 14,098,961 49 26,525,960 93.5 % Suburban Office 7 862,800 — — 7 862,800 81.6 % Total commercial properties 35 13,289,799 21 14,098,961 56 27,388,760 93.0 % Residential: Manhattan Residential 1 82,250 8 1,663,774 9 1,746,024 79.1 % Total portfolio 36 13,372,049 29 15,762,735 65 29,134,784 92.2 % (1) The weighted average occupancy for commercial properties represents the total occupied square footage divided by the total square footage at acquisition. The weighted average occupancy for residential properties represents the total occupied units divided by the total available units.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases)	The following summarizes our identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases) as of March 31, 2021 and December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Identified intangible assets (included in other assets): Gross amount $ 239,562 $ 215,673 Accumulated amortization (204,386) (190,523) Net (1) $ 35,176 $ 25,150 Identified intangible liabilities (included in deferred revenue): Gross amount $ 242,334 $ 241,409 Accumulated amortization (233,766) (230,479) Net (1) $ 8,568 $ 10,930 (1) As of March 31, 2021 and December 31, 2020, no net intangible assets and no net intangible liabilities were reclassified to assets held for sale or liabilities related to assets held for sale.
Schedule of marketable securities	At March 31, 2021 and December 31, 2020, we held the following marketable securities (in thousands): March 31, 2021 December 31, 2020 Commercial mortgage-backed securities $ 23,784 $ 28,570 Total marketable securities available-for-sale $ 23,784 $ 28,570
Schedules of Concentration of Risk, by Risk Factor	For the three months ended March 31, 2021, the following properties contributed more than 5.0% of our annualized cash rent from office properties, including our share of annualized cash rent from joint venture office properties: Property Three months ended March 31, 2021 11 Madison Avenue 9.2% 420 Lexington Avenue (Graybar) 7.2% 1185 Avenue of the Americas 7.1% 1515 Broadway 6.9% 220 East 42nd Street 6.2% 280 Park Avenue 5.8% 485 Lexington Avenue 5.1%

Property Acquisitions (Tables)

Property Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition	The following table summarizes the properties acquired during the three months ended March 31, 2021: Property Acquisition Date Property Type Approximate Square Feet Gross Asset Valuation (in millions) 885 Third Avenue (1) January 2021 Fee Interest 625,000 $ 387.9 (1) In January 2021, pursuant to the partnership documents of our 885 Third Avenue investment, certain participating rights of the common member expired. As a result, it was determined that this investment is a VIE of which we are the primary beneficiary, and the investment was consolidated in our financial statements. Upon consolidating the entity, the assets and liabilities of the entity were recorded at fair value. Prior to January 2021, the investment was accounted for under the equity method. See Note 6, "Investments in Unconsolidated Joint Ventures" and Note 16, "Fair Value Measurements."

Properties Held for Sale and _2

Properties Held for Sale and Property Dispositions (Tables)	3 Months Ended
	Mar. 31, 2021
Discontinued Operations and Disposal Groups [Abstract]
Summary of Properties Sold	The following table summarizes the properties disposed of during the three months ended March 31, 2021: Property Disposition Date Property Type Approximate Square Feet Gross Asset Valuation (in millions) (Loss) Gain (in millions) 712 Madison Avenue (1) January 2021 Fee Interest 6,600 $ 43.0 $ (1.4) 133 Greene Street (2) February 2021 Fee Interest 6,425 15.8 0.2 106 Spring Street (2) March 2021 Fee Interest 5,928 35.0 (2.8) (1) Disposition resulted from the buyer exercising its purchase option under a ground lease arrangement. (2) In the first quarter of 2021, the property was foreclosed on by the lender in conjunction with the related debt extinguishment.

Debt and Preferred Equity Inv_2

Debt and Preferred Equity Investments (Tables)	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Schedule of debt and preferred equity book balance roll forward	Below is a summary of the activity in our debt and preferred equity investments for the three months ended March 31, 2021 and the twelve months ended December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Balance at beginning of year (1) $ 1,076,542 $ 1,580,306 Debt investment originations/fundings/accretion (2) 17,465 389,300 Preferred equity investment originations/accretion (2) 3,195 167,042 Redemptions/sales/syndications/equity ownership/amortization (3) — (1,048,643) Net change in loan loss reserves — (11,463) Balance at end of period (1) $ 1,097,202 $ 1,076,542 (1) Net of unamortized fees, discounts, and premiums. (2) Accretion includes amortization of fees and discounts and paid-in-kind investment income. (3) Certain participations in debt investments that were sold or syndicated, but did not meet the conditions for sale accounting, are included in Other assets and Other liabilities on the consolidated balance sheets.
Schedule of Debt	Below is a summary of our debt and preferred equity investments as of March 31, 2021 (dollars in thousands): Floating Rate Fixed Rate Total Carrying Value Senior Financing Weighted Average Yield at End of Period Maturity (1) Type Carrying Value Face Value Interest Rate Carrying Value Face Value Interest Rate Senior Mortgage Debt $ 64,042 $ 64,649 L + 2.00% - 3.50% $ 1,249 $ 1,250 3.50% $ 65,291 $ — 4.74% 2021 - 2022 Junior Mortgage Debt 7,207 12,000 L + 7.25% 42,819 43,000 6.25% 50,026 127,000 7.82% 2021 Mezzanine Debt 281,401 285,179 L + 4.95% - 13.61% 437,503 449,102 2.90% - 14.30% 718,904 4,476,210 5.86% 2021 - 2029 Preferred Equity — — — 262,981 265,052 6.50% - 11.00% 262,981 1,962,750 9.94% 2022 - 2027 Balance at end of period $ 352,650 $ 361,828 $ 744,552 $ 758,404 $ 1,097,202 $ 6,565,960 (1) Excludes available extension options to the extent they have not been exercised as of the date of this filing.
Allowance for Credit Losses on Financing Receivables	The following table is a rollforward of our total allowance for loan losses for the three months ended March 31, 2021 and the twelve months ended December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Balance at beginning of year $ 13,213 $ 1,750 Cumulative adjustment upon adoption of ASC 326 — 27,803 Current period provision for loan loss — 20,693 Write-offs charged against the allowance (1) — (37,033) Balance at end of period (2) $ 13,213 $ 13,213 (1) Includes $19.0 million of charges recorded against investments that were sold during the year ended December 31, 2020. These charges are included in loan loss and other investment reserves, net of recoveries, in our consolidated statements of operations for the year ended December 31, 2020. (2) As of March 31, 2021, we had recorded an allowance for loan loss on all financing receivables on non-accrual except for one debt investment with a carrying value of $225.4 million.
Schedule of Investment in Financing Receivables and Risk Rating	The following table sets forth the carrying value of our debt and preferred equity investment portfolio by risk rating as of March 31, 2021 and December 31, 2020 (dollars in thousands): Risk Rating March 31, 2021 December 31, 2020 1 - Low Risk Assets - Low probability of loss $ 712,994 $ 695,035 2 - Watch List Assets - Higher potential for loss 367,859 365,167 3 - High Risk Assets - Loss more likely than not 16,349 16,340 $ 1,097,202 $ 1,076,542 The following table sets forth the carrying value of our debt and preferred equity investment portfolio by year of origination and risk rating as of March 31, 2021 (dollars in thousands): As of March 31, 2021 Risk Rating 2021 (1) 2020 (1) 2019 (1) Prior (1) Total 1 - Low Risk Assets - Low probability of loss $ — $ 361,444 $ 56,639 $ 294,911 $ 712,994 2 - Watch List Assets - Higher potential for loss — — 241,285 126,574 367,859 3 - High Risk Assets - Loss more likely than not — — — 16,349 16,349 $ — $ 361,444 $ 297,924 $ 437,834 $ 1,097,202 (1) Year in which the investment was originated or acquired by us or in which a material modification occurred.
Summary of debt investments	As of March 31, 2021 and December 31, 2020, we held the following debt investments with an aggregate weighted average current yield of 5.90% at March 31, 2021 (dollars in thousands): Loan Type March 31, 2021 March 31, 2021 Senior March 31, 2021 Carrying Value (1) December 31, 2020 (1) Maturity (2) Fixed Rate Investments: Junior Mortgage (3a) $ — $ 67,000 $ 42,820 $ 32,888 July 2021 Mezzanine Loan — 15,000 3,500 3,500 September 2021 Mortgage/Mezzanine Loan — 63,750 56,246 56,244 October 2021 Mezzanine Loan — 280,000 41,652 41,057 August 2022 Mezzanine Loan (4) — 359,237 225,367 225,204 June 2023 Mezzanine Loan (3b)(5) — 105,000 13,366 13,366 June 2024 Mezzanine Loan — 95,000 30,000 30,000 January 2025 Mezzanine Loan — 1,712,750 55,250 55,250 June 2027 Mezzanine Loan — 85,000 20,000 20,000 December 2029 Total fixed rate $ — $ 2,782,737 $ 488,201 $ 477,509 Floating Rate Investments: Mezzanine Loan (6) $ — $ 275,000 $ 49,992 $ 49,956 April 2021 Junior Mortgage Participation/Mezzanine Loan — 60,000 15,742 15,733 July 2021 Mezzanine Loan 5,761 177,415 36,639 35,318 July 2021 Mezzanine Loan — 61,744 29,130 29,106 July 2021 Mezzanine Loan (3c) — 1,115,000 129,330 127,915 March 2022 Mortgage and Mezzanine Loan 6,769 — 60,922 60,532 May 2022 Mortgage and Mezzanine Loan 42,117 — 15,918 14,011 December 2022 Mezzanine Loan 52,288 71,314 21,560 19,889 May 2023 Total floating rate $ 106,935 $ 1,760,473 $ 359,233 $ 352,460 Allowance for loan loss $ — $ — $ (13,213) $ (13,213) Total $ 106,935 $ 4,543,210 $ 834,221 $ 816,756 (1) Carrying value is net of discounts, premiums, original issue discounts and deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options. (3) Carrying value is net of the following amounts that were sold or syndicated, which are included in Other assets and Other liabilities on the consolidated balance sheets as a result of the transfers not meeting the conditions for sale accounting: (a) $66.6 million (b) $12.0 million, and (c) $0.4 million. (4) This loan was put on non-accrual in July 2020 and remains on non-accrual at March 31, 2021. No investment income has been recognized subsequent to it being put on non-accrual. (5) This loan went into default and was put on non-accrual in June 2020 and remains on non-accrual at March 31, 2021. No investment income has been recognized subsequent to it being put on non-accrual. The Company is in discussions with the borrower. (6) In April 2021, the maturity date of this loan was extended one year to April 2022.
Summary of preferred equity investments	As of March 31, 2021 and December 31, 2020, we held the following preferred equity investments with an aggregate weighted average current yield of 9.94% at March 31, 2021 (dollars in thousands): Type March 31, 2021 March 31, 2021 Senior March 31, 2021 Carrying Value (1) December 31, 2020 Carrying Value (1) Mandatory Redemption (2) Preferred Equity $ — $ 1,712,750 $ 156,169 $ 154,691 June 2022 Preferred Equity — 250,000 106,812 105,095 February 2027 Total Preferred Equity $ — $ 1,962,750 $ 262,981 $ 259,786 Allowance for loan loss $ — $ — $ — $ — Total $ — $ 1,962,750 $ 262,981 $ 259,786 (1) Carrying value is net of deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options.

Investments in Unconsolidated_2

Investments in Unconsolidated Joint Ventures (Tables)	3 Months Ended
	Mar. 31, 2021
Equity Method Investments and Joint Ventures [Abstract]
Schedule of general information on joint ventures	The table below provides general information on each of our joint ventures as of March 31, 2021: Property Partner Ownership (1) Economic (1) Unaudited Approximate Square Feet 100 Park Avenue Prudential Real Estate Investors 49.90% 49.90% 834,000 717 Fifth Avenue Wharton Properties/Private Investor 10.92% 10.92% 119,500 800 Third Avenue Private Investors 60.52% 60.52% 526,000 919 Third Avenue New York State Teacher's Retirement System 51.00% 51.00% 1,454,000 11 West 34th Street Private Investor/Wharton Properties 30.00% 30.00% 17,150 280 Park Avenue Vornado Realty Trust 50.00% 50.00% 1,219,158 1552-1560 Broadway (2) Wharton Properties 50.00% 50.00% 57,718 10 East 53rd Street Canadian Pension Plan Investment Board 55.00% 55.00% 354,300 21 East 66th Street (3) Private Investors 32.28% 32.28% 13,069 650 Fifth Avenue (4) Wharton Properties 50.00% 50.00% 69,214 121 Greene Street Wharton Properties 50.00% 50.00% 7,131 Stonehenge Portfolio Various Various Various 1,439,016 605 West 42nd Street (5) The Moinian Group 20.00% 20.00% 927,358 11 Madison Avenue PGIM Real Estate 60.00% 60.00% 2,314,000 400 East 57th Street (6) BlackRock, Inc and Stonehenge Partners 51.00% 41.00% 290,482 One Vanderbilt National Pension Service of Korea/Hines Interest LP 71.01% 71.01% 1,657,198 Worldwide Plaza RXR Realty / New York REIT / Private Investor 24.35% 24.35% 2,048,725 1515 Broadway Allianz Real Estate of America 56.87% 56.87% 1,750,000 2 Herald Square Israeli Institutional Investor 51.00% 51.00% 369,000 Property Partner Ownership (1) Economic (1) Unaudited Approximate Square Feet 115 Spring Street Private Investor 51.00% 51.00% 5,218 15 Beekman (7) A fund managed by Meritz Alternative Investment Management 20.00% 20.00% 221,884 85 Fifth Avenue Wells Fargo 36.30% 36.30% 12,946 One Madison Avenue (8) National Pension Service of Korea/Hines Interest LP 50.50% 50.50% 1,048,700 (1) Ownership interest and economic interest represent the Company's interests in the joint venture as of March 31, 2021. Changes in ownership or economic interests within the current year are disclosed in the notes below. (2) The joint venture also owns a long-term leasehold interest in the retail space and certain other spaces at 1560 Broadway, which is adjacent to 1552 Broadway. (3) We hold a 32.28% interest in three retail units and one residential unit at the property and a 16.14% interest in three residential units at the property. (4) The joint venture owns a long-term leasehold interest in the retail space at 650 Fifth Avenue. (5) In April 2021, we entered into contract to sell our interest in the property. This transaction is expected to close in the second quarter of 2021 subject to customary closing conditions. (6) In October 2016, we sold a 49% interest in this property. Our interest in the property was sold within a consolidated joint venture owned 90% by the Company and 10% by Stonehenge. The transaction resulted in the deconsolidation of the venture's remaining 51% interest in the property. Our joint venture with Stonehenge remains consolidated resulting in the combined 51% interest being shown within investments in unconsolidated joint ventures on our balance sheet. In April 2021, we entered into contract to sell our interest in the property. In connection with this contract, we recorded a charge of $5.7 million, which is included in depreciable real estate reserves and impairment in the consolidated statements of operations. This transaction is expected to close in the third quarter of 2021 subject to customary closing conditions. (7) In 2020, the Company formed a joint venture, which then entered into a long-term sublease with the Company. (8) In 2020, the Company admitted partners to the One Madison Avenue development project, which resulted in the Company no longer retaining a controlling interest in the entity, as defined in ASC 810, and the deconsolidation of our remaining 50.5% interest. We recorded our investment at fair value, which resulted in the recognition of a fair value adjustment of $187.5 million in 2020 and a fair value adjustment of $2.7 million during the three months ended March 31, 2021. The fair value of our investment was determined by the terms of the joint venture agreement governing the capitalization of the project. The partners have committed aggregate equity to the project totaling no less than $492.2 million and their ownership interest in the joint venture is based on their capital contributions, up to an aggregate maximum of 49.5%. At March 31, 2021, the total of the two partners' ownership interests based on equity contributed was 9.0%.
Schedule of Investments in Unconsolidated Joint Ventures Disposed	The following table summarizes the investments in unconsolidated joint ventures disposed of during the three months ended March 31, 2021: Property Ownership Interest Disposed Disposition Date Gross Asset Valuation (in thousands) Gain (Loss) on Sale (in thousands) (1) 885 Third Avenue (2) N/A January 2021 N/A N/A 55 West 46th Street - Tower 46 25.0% March 2021 $ 275.0 $ (15.2) (1) Represents the Company's share of the gain or loss. (2) In January 2021, pursuant to the partnership documents of our 885 Third Avenue investment, certain participating rights of the common member expired. As a result, it was determined that we are the primary beneficiary of the VIE and the investment was consolidated in our financial statements. See Note 3, "Property Acquisitions."
Schedule of first mortgage notes payable collateralized by the respective joint venture properties and assignment of leases	The mortgage notes and other loans payable collateralized by the respective joint venture properties and assignment of leases at March 31, 2021 and December 31, 2020, respectively, are as follows (dollars in thousands): Property Economic (1) Initial Maturity Final Maturity Date (2) Interest Rate (3) March 31, 2021 December 31, 2020 Fixed Rate Debt: 717 Fifth Avenue (mortgage) 10.92 % July 2022 July 2022 4.45 % $ 300,000 $ 300,000 717 Fifth Avenue (mezzanine) 10.92 % July 2022 July 2022 5.50 % 355,328 355,328 650 Fifth Avenue (mortgage) 50.00 % October 2022 October 2022 4.46 % 210,000 210,000 650 Fifth Avenue (mezzanine) 50.00 % October 2022 October 2022 5.45 % 65,000 65,000 21 East 66th Street 32.28 % April 2023 April 2028 3.60 % 12,000 12,000 Property Economic (1) Initial Maturity Final Maturity Date (2) Interest Rate (3) March 31, 2021 December 31, 2020 919 Third Avenue 51.00 % June 2023 June 2023 5.12 % 500,000 500,000 1515 Broadway 56.87 % March 2025 March 2025 3.93 % 815,876 820,607 11 Madison Avenue 60.00 % September 2025 September 2025 3.84 % 1,400,000 1,400,000 800 Third Avenue 60.52 % February 2026 February 2026 3.37 % 177,000 177,000 400 East 57th Street (4) 41.00 % November 2026 November 2026 3.00 % 97,024 97,024 Worldwide Plaza 24.35 % November 2027 November 2027 3.98 % 1,200,000 1,200,000 Stonehenge Portfolio (5) Various Various Various 3.50 % 195,899 195,899 885 Third Avenue (6) — 272,000 Total fixed rate debt $ 5,328,127 $ 5,604,858 Floating Rate Debt: 280 Park Avenue 50.00 % September 2021 September 2024 L+ 1.73 % $ 1,200,000 $ 1,200,000 One Vanderbilt (7) 71.01 % September 2021 September 2023 L+ 2.50 % 1,283,292 1,210,329 1552 Broadway 50.00 % October 2021 October 2022 L+ 2.65 % 195,000 195,000 2 Herald Square 51.00 % November 2021 November 2023 L+ 1.45 % 214,500 214,500 11 West 34th Street 30.00 % January 2022 January 2023 L+ 1.45 % 23,000 23,000 121 Greene Street (8) 50.00 % November 2022 November 2022 L+ 2.00 % 13,771 15,000 115 Spring Street 51.00 % September 2023 September 2023 L+ 3.40 % 65,550 65,550 100 Park Avenue 49.90 % December 2023 December 2025 L+ 2.25 % 360,000 360,000 15 Beekman (9) 20.00 % January 2024 July 2025 L+ 1.50 % 19,165 11,212 10 East 53rd Street 55.00 % February 2025 February 2025 L+ 1.35 % 220,000 220,000 One Madison Avenue (10) 50.50 % November 2025 November 2026 L+ 3.35 % 40,104 — 605 West 42nd Street (11) 20.00 % August 2027 August 2027 L+ 1.44 % 550,000 550,000 21 East 66th Street 32.28 % June 2033 June 2033 T+ 2.75 % 666 677 55 West 46th Street — 192,524 Total floating rate debt $ 4,185,048 $ 4,257,792 Total joint venture mortgages and other loans payable $ 9,513,175 $ 9,862,650 Deferred financing costs, net (98,252) (113,446) Total joint venture mortgages and other loans payable, net $ 9,414,923 $ 9,749,204 (1) Economic interest represents the Company's interests in the joint venture as of March 31, 2021. Changes in ownership or economic interests, if any, within the current year are disclosed in the notes to the investment in unconsolidated joint ventures table above. (2) Reflects exercise of all available options. The ability to exercise extension options may be subject to certain tests based on the operating performance of the property. (3) Interest rates as of March 31, 2021, taking into account interest rate hedges in effect during the period. Floating rate debt is presented with the stated spread over the 30-day LIBOR ("L") or 1-year Treasury ("T"). (4) In April 2021, we entered into a contract to sell our interest in the property. This transaction is expected to close in the third quarter of 2021 subject to customary closing conditions. (5) Comprised of three mortgages totaling $132.4 million that mature in April 2028 and two mortgages totaling $63.5 million that mature in July 2029. (6) This loan was repaid in the first quarter of 2021, and as of March 31, 2021, the property is consolidated in our financial statements. See Note 3, "Property Acquisitions." (7) This loan is a $1.75 billion construction facility with reductions in interest cost based on meeting certain conditions, the first of which has been satisfied, and has an initial term of three years with two one year extension options. Advances under the loan are subject to costs incurred. In conjunction with the loan, we provided partial guarantees for interest and principal payments, the amounts of which are based on certain construction milestones and operating metrics. (8) In March 2021, the maturity date of this loan was extended by one year. (9) This loan is a $125.0 million construction facility. Advances under the loan are subject to costs incurred. (10) The loan is a $1.25 billion construction facility with an initial term of five years with one one year extension option. Advances under the loan are subject to costs incurred. In conjunction with the loan, we provided partial guarantees for interest and principal payments, the amounts of which are based on certain construction milestones and operating metrics. (11) In April 2021, we entered into contract to sell our interest in the property. This transaction is expected to close in the second quarter of 2021 subject to customary closing conditions.
Schedule of combined balance sheets for the unconsolidated joint ventures	The combined balance sheets for the unconsolidated joint ventures, at March 31, 2021 and December 31, 2020 are as follows (in thousands): March 31, 2021 December 31, 2020 Assets (1) Commercial real estate property, net $ 15,243,331 $ 16,143,880 Cash and restricted cash 317,753 357,076 Tenant and other receivables, related party receivables, and deferred rents receivable 412,203 403,883 Other assets 1,950,444 2,001,612 Total assets $ 17,923,731 $ 18,906,451 Liabilities and equity (1) Mortgages and other loans payable, net $ 9,414,923 $ 9,749,204 Deferred revenue 1,311,191 1,341,571 Lease liabilities 985,622 1,002,563 Other liabilities 373,400 464,107 Equity 5,838,595 6,349,006 Total liabilities and equity $ 17,923,731 $ 18,906,451 Company's investments in unconsolidated joint ventures $ 3,698,701 $ 3,823,322 (1) At March 31, 2021, $174.2 million of net unamortized basis differences between the amount at which our investments are carried and our share of equity in net assets of the underlying property will be amortized through equity in net income (loss) from unconsolidated joint ventures over the remaining life of the underlying items having given rise to the differences.
Schedule of combined statements of income for the unconsolidated joint ventures	The combined statements of operations for the unconsolidated joint ventures, from acquisition date through the three months ended March 31, 2021 and 2020, are as follows (in thousands): Three Months Ended March 31, 2021 2020 Total revenues $ 301,541 $ 282,520 Operating expenses 46,233 51,590 Real estate taxes 54,592 53,372 Operating lease rent 5,644 6,361 Interest expense, net of interest income 78,749 86,324 Amortization of deferred financing costs 6,384 4,814 Depreciation and amortization 114,879 98,584 Total expenses 306,481 301,045 Net loss before gain on sale $ (4,940) $ (18,525) Company's equity in net loss from unconsolidated joint ventures $ (2,864) $ (12,814)

Deferred Costs (Tables)

Deferred Costs (Tables)	3 Months Ended
	Mar. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of components of deferred costs	Deferred costs at March 31, 2021 and December 31, 2020 consisted of the following (in thousands): March 31, 2021 December 31, 2020 Deferred leasing costs $ 448,197 $ 447,002 Less: accumulated amortization (277,945) (269,834) Deferred costs, net $ 170,252 $ 177,168

Mortgages and Other Loans Pay_2

Mortgages and Other Loans Payable (Tables)	3 Months Ended
	Mar. 31, 2021
Mortgages and Other Loans Payable
Schedule of first mortgages and other loans payable collateralized by the respective properties and assignment of leases	The mortgages and other loans payable collateralized by the respective properties and assignment of leases or debt investments at March 31, 2021 and December 31, 2020, respectively, were as follows (dollars in thousands): Property Initial Maturity Final Maturity Date (1) Interest Rate (2) March 31, 2021 December 31, 2020 Fixed Rate Debt: 100 Church Street July 2022 July 2022 4.68% $ 203,697 $ 204,875 420 Lexington Avenue October 2024 October 2040 3.99% 292,672 294,035 Landmark Square January 2027 January 2027 4.90% 100,000 100,000 485 Lexington Avenue February 2027 February 2027 4.25% 450,000 450,000 1080 Amsterdam (3) February 2027 February 2027 3.59% 34,773 34,773 Total fixed rate debt $ 1,081,142 $ 1,083,683 Floating Rate Debt: 185 Broadway (4) November 2021 November 2023 L+ 2.85% $ 168,870 $ 158,478 609 Fifth Avenue March 2022 March 2022 L+ 2.95% 57,651 57,651 220 East 42nd Street June 2023 June 2025 L+ 2.75% 510,000 510,000 719 Seventh Avenue September 2023 September 2023 L+ 1.20% 50,000 50,000 133 Greene Street — 15,523 106 Spring Street — 38,025 FHLB Facility — 10,000 FHLB Facility — 15,000 FHLB Facility — 35,000 712 Madison Avenue — 28,000 2017 Master Repurchase Agreement (5) — — Total floating rate debt $ 786,521 $ 917,677 Total mortgages and other loans payable $ 1,867,663 $ 2,001,360 Deferred financing costs, net of amortization (18,962) (21,388) Total mortgages and other loans payable, net $ 1,848,701 $ 1,979,972 (1) Reflects exercise of all available options. The ability to exercise extension options may be subject to certain tests based on the operating performance of the property. (2) Interest rate as of March 31, 2021, taking into account interest rate hedges in effect during the period. Floating rate debt is presented with the stated spread over the 30-day LIBOR, unless otherwise specified. (3) The loan is comprised of a $33.9 million mortgage loan and $0.9 million mezzanine loan with a fixed interest rate of 350 basis points and 700 basis points, respectively, for the first five years and is prepayable without penalty at the end of fifth year. (4) This loan is a $225.0 million construction facility, with reductions in interest cost based on meeting certain conditions, and has an initial three year term with two one year extension options. Advances under the loan are subject to incurred costs and funded equity requirements. (5) In June 2020, we exercised a one year extension option which extended the maturity date to June 2021. At March 31, 2021, there was no outstanding balance on the $400 million facility.

Corporate Indebtedness (Tables)

Corporate Indebtedness (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of senior unsecured notes and other related disclosures by scheduled maturity date	The following table sets forth our senior unsecured notes and other related disclosures as of March 31, 2021 and December 31, 2020, respectively, by scheduled maturity date (dollars in thousands): Issuance March 31, 2021 March 31, 2021 December 31, Interest Rate (1) Initial Term Maturity Date August 7, 2018 (2) (3) $ 350,000 $ 350,000 $ 350,000 1.52 % 3 August 2021 October 5, 2017 (2) 500,000 499,830 499,803 3.25 % 5 October 2022 November 15, 2012 (4) 300,000 301,817 302,086 4.50 % 10 December 2022 December 17, 2015 (5) 100,000 100,000 100,000 4.27 % 10 December 2025 $ 1,250,000 $ 1,251,647 $ 1,251,889 Deferred financing costs, net (3,025) (3,670) $ 1,250,000 $ 1,248,622 $ 1,248,219 (1) Interest rate as of March 31, 2021, taking into account interest rate hedges in effect during the period. (2) Issued by the Operating Partnership with the Company as the guarantor. (3) The notes are subject to redemption at the Company's option, in whole but not in part, at a redemption price equal to 100% of the principal amount of the notes, plus unpaid accrued interest thereon to the redemption date. In April 2020, the Company entered into $350.0 million of fixed rate interest swaps at a rate of 0.54375% through August 2021. (4) In October 2017, the Company and the Operating Partnership as co-obligors issued an additional $100.0 million of 4.50% senior unsecured notes due December 2022. The notes were priced at 105.334% of par. (5) Issued by the Company and the Operating Partnership as co-obligors.
Schedule of combined aggregate principal maturities	Combined aggregate principal maturities of mortgages and other loans payable, the 2017 credit facility, trust preferred securities, senior unsecured notes and our share of joint venture debt as of March 31, 2021, including as-of-right extension options, were as follows (in thousands): Scheduled Mortgages and Other Loans Payable Revolving Unsecured Term Loans Trust Senior Total Joint Remaining 2021 $ 8,031 $ 168,870 $ — $ — $ — $ 350,000 $ 526,901 $ 1,126,896 2022 8,765 255,435 — — — 800,000 1,064,200 227,701 2023 6,594 560,000 630,000 1,300,000 — — 2,496,594 491,066 2024 5,280 272,749 — 200,000 — — 478,029 620,843 2025 823 — — — — 100,000 100,823 1,403,266 Thereafter 924 580,192 — — 100,000 — 681,116 552,813 $ 30,417 $ 1,837,246 $ 630,000 $ 1,500,000 $ 100,000 $ 1,250,000 $ 5,347,663 $ 4,422,585
Schedule of consolidated interest expense, excluding capitalized interest	Consolidated interest expense, excluding capitalized interest, was comprised of the following (in thousands): Three Months Ended March 31, 2021 2020 Interest expense before capitalized interest $ 39,868 $ 56,813 Interest on financing leases 1,492 1,663 Interest capitalized (17,583) (20,483) Interest income (389) (499) Interest expense, net $ 23,388 $ 37,494

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2021
Related Party Transactions [Abstract]
Schedule of amounts due from/to related parties	Amounts due from joint ventures and related parties at March 31, 2021 and December 31, 2020 consisted of the following (in thousands): March 31, 2021 December 31, 2020 Due from joint ventures $ 26,500 $ 27,006 Other 7,810 7,651 Related party receivables $ 34,310 $ 34,657

Noncontrolling Interests on t_2

Noncontrolling Interests on the Company's Consolidated Financial Statements (Tables)	3 Months Ended
	Mar. 31, 2021
Noncontrolling Interest [Abstract]
Schedule of Noncontrolling Interest	Below is a summary of the activity relating to the noncontrolling interests in the Operating Partnership for the three months ended March 31, 2021 and the twelve months ended December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Balance at beginning of period $ 358,262 $ 409,862 Distributions (4,148) (12,652) Issuance of common units 4,483 12,018 Redemption and conversion of common units (13,261) (36,085) Net (loss) income (476) 20,016 Accumulated other comprehensive income (loss) allocation 2,655 (2,299) Fair value adjustment 26,609 (32,598) Balance at end of period $ 374,124 $ 358,262
Schedule of Preferred Unit Activity	Below is a summary of the preferred units of limited partnership interest in the Operating Partnership as of March 31, 2021: Issuance Stated Distribution Rate Number of Units Authorized Number of Units Issued Number of Units Outstanding Annual Dividend Per Unit (1) Liquidation Preference Per Unit (2) Conversion Price Per Unit (3) Date of Issuance Series A (4) 3.50 % 109,161 109,161 109,161 $ 35.0000 $ 1,000.00 $ — August 2015 Series F 7.00% 60 60 60 $ 70.0000 $ 1,000.00 $ 29.12 January 2007 Series G (5) 4.50% 1,902,000 1,902,000 718,697 $ 1.1250 $ 25.00 $ 88.50 January 2012 Series K 3.50% 700,000 563,954 341,677 $ 0.8750 $ 25.00 $ 134.67 August 2014 Series L 4.00% 500,000 378,634 372,634 $ 1.0000 $ 25.00 $ — August 2014 Series M 3.75% 1,600,000 1,600,000 96,357 $ 0.9375 $ 25.00 $ — February 2015 Series P 4.00% 200,000 200,000 200,000 $ 1.0000 $ 25.00 $ — July 2015 Series Q 3.50% 268,000 268,000 268,000 $ 0.8750 $ 25.00 $ 148.95 July 2015 Series R 3.50% 400,000 400,000 400,000 $ 0.8750 $ 25.00 $ 154.89 August 2015 Series S 4.00% 1,077,280 1,077,280 1,077,280 $ 1.0000 $ 25.00 $ — August 2015 Series V 3.50% 40,000 40,000 40,000 $ 0.8750 $ 25.00 $ — May 2019 Series W (6) (6) 1 1 1 (6) (6) (6) January 2020 (1) Dividends are cumulative, subject to certain provisions. (2) Units are redeemable at any time at par for cash at the option of the unitholder unless otherwise specified. (3) If applicable, units are convertible into a number of common units of limited partnership interest in the Operating Partnership equal to (i) the liquidation preference plus accumulated and unpaid distributions on the conversion date divided by (ii) the amount shown in the table. (4) Issued through a consolidated subsidiary. The units are convertible on a one-for-one basis, into the Series B Preferred Units of limited partnership interest, or the Subsidiary Series B Preferred Units. The Subsidiary Series B Preferred Units can be converted at any time, at the option of the unitholder, into a number of common stock equal to 6.71348 shares of common stock for each Subsidiary Series B Preferred Unit. As of March 31, 2021, no Subsidiary Series B Preferred Units have been issued. (5) Common units of limited partnership interest in the Operating Partnership issued in a conversion may be redeemed in exchange for our common stock on a 1-to-1 basis. The Series G Preferred Units also provide the holder with the right to require the Operating Partnership to repurchase the Series G Preferred Units for cash before January 31, 2022. (6) The Series W preferred unit was issued in January 2020 in exchange for the then-outstanding Series O preferred unit. The holder of the Series W preferred unit is entitled to quarterly dividends in an amount calculated as (i) 1,350 multiplied by (ii) the current distribution per common unit of limited partnership in SL Green Operating Partnership. The holder has the right to require the Operating Partnership to repurchase the Series W unit for cash, or convert the Series W unit for Class B units, in each case at a price that is determined based on the closing price of the Company's common stock at the time such right is exercised. The unit's liquidation preference is the fair market value of the unit plus accrued distributions at the time of a liquidation event. Below is a summary of the activity relating to the preferred units in the Operating Partnership for the three months ended March 31, 2021 and the twelve months ended December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Balance at beginning of period $ 202,169 $ 283,285 Issuance of preferred units — — Redemption of preferred units (3,631) (82,750) Dividends paid on preferred units (1,731) (6,163) Accrued dividends on preferred units 1,696 7,797 Balance at end of period $ 198,503 $ 202,169

Stockholders' Equity of the C_2

Stockholders' Equity of the Company (Tables)	3 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Class of Treasury Stock	At March 31, 2021, share repurchases, excluding the redemption of OP units, executed under the program were as follows: Period Shares repurchased Average price paid per share Cumulative number of shares repurchased as part of the repurchase plan or programs Year ended 2017 8,105,881 $104.61 8,105,881 Year ended 2018 9,468,617 $99.03 17,574,498 Year ended 2019 4,465,857 $86.06 22,040,355 Year Ended 2020 8,529,279 $62.39 30,569,634 Three months ended March 31, 2021 1,306,460 $61.46 31,876,094
Schedule of Common Stock Issued and Proceeds Received Dividend Reinvestments	The following table summarizes SL Green common stock issued, and proceeds received from dividend reinvestments and/or stock purchases under the DRSPP for the three months ended March 31, 2021 and 2020, respectively (dollars in thousands): Three Months Ended March 31, 2021 2020 Shares of common stock issued 5,483 1,727 Dividend reinvestments/stock purchases under the DRSPP $ 351 $ 166
Schedule of Earnings Per Share	SL Green's earnings per share for the three months ended March 31, 2021 and 2020 are computed as follows (in thousands): Three Months Ended March 31, Numerator 2021 2020 Basic Earnings: Net (loss) income attributable to SL Green common stockholders $ (7,464) $ 114,801 Less: distributed earnings allocated to participating securities (371) (113) Less: undistributed earnings allocated to participating securities — (464) Net (loss) income attributable to SL Green common stockholders (numerator for basic earnings per share) $ (7,835) $ 114,224 Add back: dilutive effect of earnings allocated to participating securities 371 113 Add back: undistributed earnings allocated to participating securities — 464 Add back: effect of dilutive securities (redemption of units to common shares) (476) 6,202 Net (loss) income attributable to SL Green common stockholders (numerator for diluted earnings per share) $ (7,940) $ 121,003 Three Months Ended March 31, Denominator 2021 2020 Basic Shares: Weighted average common stock outstanding 69,010 75,656 Effect of Dilutive Securities: Operating Partnership units redeemable for common shares 4,148 4,220 Stock-based compensation plans 595 476 Contingently issuable shares from special dividend declared December 4, 2020 and issued January 15, 2021 317 — Diluted weighted average common stock outstanding 74,070 80,352

Partners' Capital of the Oper_2

Partners' Capital of the Operating Partnership (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Schedule of calculation of numerator and denominator in earnings per unit	The Operating Partnership's earnings per unit for the three months ended March 31, 2021 and 2020, respectively, are computed as follows (in thousands): Three Months Ended March 31, Numerator 2021 2020 Basic Earnings: Net (loss) income attributable to SLGOP common unitholders $ (7,940) $ 121,003 Less: distributed earnings allocated to participating securities (371) (113) Less: undistributed earnings allocated to participating securities — (464) Net (loss) income attributable to SLGOP common unitholders (numerator for basic earnings per unit) $ (8,311) $ 120,426 Add back: dilutive effect of earnings allocated to participating securities 371 113 Add back: undistributed earnings allocated to participating securities — 464 Net (loss) income attributable to SLGOP common unitholders (numerator for diluted earnings per unit) $ (7,940) $ 121,003 Three Months Ended March 31, Denominator 2021 2020 Basic units: Weighted average common units outstanding 73,158 79,876 Effect of Dilutive Securities: Stock-based compensation plans 595 476 Contingently issuable units from special distribution declared December 4, 2020 and issued January 15, 2021 317 — Diluted weighted average common units outstanding 74,070 80,352

Share-based Compensation (Table

Share-based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Summary of the status of stock options and changes during the period	A summary of the status of the Company's stock options as of March 31, 2021 and December 31, 2020, and changes during the three months ended March 31, 2021 and year ended December 31, 2020 are as follows: March 31, 2021 December 31, 2020 Options Outstanding Weighted Average Options Outstanding Weighted Average Balance at beginning of period 784,995 $ 102.62 1,007,665 $ 105.35 Granted — — — — Exercised — — — — Lapsed or canceled (9,716) 86.13 (222,670) 114.97 Balance at end of period 775,279 $ 102.83 784,995 $ 102.62 Options exercisable at end of period 775,278 $ 102.83 782,022 $ 102.62
Summary of restricted stock and charges during the period	A summary of the Company's restricted stock as of March 31, 2021 and December 31, 2020 and changes during the three months ended March 31, 2021 and the year ended December 31, 2020, are as follows: March 31, 2021 December 31, 2020 Balance at beginning of period 3,439,674 3,465,347 Granted 145,845 8,959 Canceled (12,437) (34,632) Balance at end of period 3,573,082 3,439,674 Vested during the period 117,487 128,891 Compensation expense recorded $ 2,067,125 $ 10,895,459 Total fair value of restricted stock granted during the period $ 9,214,531 $ 734,315

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Schedule of accumulated other comprehensive income (loss)	The following tables set forth the changes in accumulated other comprehensive loss by component as of March 31, 2021 (in thousands): Net unrealized loss on derivative instruments ( 1 ) SL Green’s share of joint venture net unrealized loss on derivative instruments ( 2 ) Net unrealized gain (loss) on marketable securities Total Balance at December 31, 2020 $ (57,415) $ (10,853) $ 1,021 $ (67,247) Other comprehensive income before reclassifications 9,771 33,024 (247) 42,548 Amounts reclassified from accumulated other comprehensive loss 4,196 1,606 — 5,802 Balance at March 31, 2021 $ (43,448) $ 23,777 $ 774 $ (18,897) (1) Amount reclassified from accumulated other comprehensive loss is included in interest expense in the respective consolidated statements of operations. As of March 31, 2021 and December 31, 2020, the deferred net gains from these terminated hedges, which is included in accumulated other comprehensive loss relating to net unrealized loss on derivative instrument, was $(0.6) million and $(0.5) million, respectively. (2) Amount reclassified from accumulated other comprehensive loss is included in equity in net loss from unconsolidated joint ventures in the respective consolidated statements of operations.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair value measurements, recurring and nonrecurring	The following tables set forth the assets and liabilities that we measure at fair value on a recurring and non-recurring basis by their levels in the fair value hierarchy at March 31, 2021 and December 31, 2020 (in thousands): March 31, 2021 Total Level 1 Level 2 Level 3 Assets: Marketable securities $ 23,784 $ — $ 23,784 $ — Interest rate cap and swap agreements (included in Other assets) $ 365 $ — $ 365 $ — Liabilities: Interest rate cap and swap agreements (included in Other liabilities) $ 47,033 $ — $ 47,033 $ — December 31, 2020 Total Level 1 Level 2 Level 3 Assets: Marketable securities $ 28,570 $ — $ 28,570 $ — Interest rate cap and swap agreements (included in Other assets) $ 28 $ — $ 28 $ — Liabilities: Interest rate cap and swap agreements (included in Other liabilities) $ 61,217 $ — $ 61,217 $ —
Fair value, by balance sheet grouping	The following table provides the carrying value and fair value of these financial instruments as of March 31, 2021 and December 31, 2020 (in thousands): March 31, 2021 December 31, 2020 Carrying Value (1) Fair Value Carrying Value (1) Fair Value Debt and preferred equity investments $ 1,097,202 (2) $ 1,076,542 (2) Fixed rate debt $ 3,932,789 $ 4,027,789 $ 3,135,572 $ 3,237,075 Variable rate debt 1,416,521 1,420,814 1,827,677 1,822,740 $ 5,349,310 $ 5,448,603 $ 4,963,249 $ 5,059,815 (1) Amounts exclude net deferred financing costs. (2) At March 31, 2021, debt and preferred equity investments had an estimated fair value ranging between $1.0 billion and $1.1 billion. At December 31, 2020, debt and preferred equity investments had an estimated fair value ranging between $1.0 billion and $1.1 billion.

Financial Instruments_ Deriva_2

Financial Instruments: Derivatives and Hedging (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of notional and fair value of derivative financial instruments and foreign currency hedges	The following table summarizes the notional value at inception and fair value of our consolidated derivative financial instruments at March 31, 2021 based on Level 2 information. The notional value is an indication of the extent of our involvement in these instruments at that time, but does not represent exposure to credit, interest rate or market risks (dollars in thousands). Notional Strike Effective Expiration Balance Sheet Location Fair Interest Rate Swap $ 350,000 0.544 % April 2020 August 2021 Other Liabilities $ (472) Interest Rate Cap 111,869 3.500 % December 2020 November 2021 Other Assets — Interest Rate Cap 510,000 3.000 % June 2020 December 2021 Other Assets — Interest Rate Swap 200,000 0.138 % February 2021 February 2022 Other Liabilities (3) Interest Rate Swap 100,000 0.136 % February 2021 February 2022 Other Assets — Interest Rate Cap 85,000 4.000 % March 2021 March 2022 Other Assets — Interest Rate Swap 100,000 0.212 % January 2021 January 2023 Other Assets 95 Interest Rate Swap 400,000 0.160 % February 2021 February 2023 Other Assets 270 Interest Rate Swap 200,000 1.131 % July 2016 July 2023 Other Liabilities (4,017) Interest Rate Swap 100,000 1.161 % July 2016 July 2023 Other Liabilities (2,077) Interest Rate Swap 150,000 2.696 % January 2019 January 2024 Other Liabilities (9,675) Interest Rate Swap 150,000 2.721 % January 2019 January 2026 Other Liabilities (13,117) Interest Rate Swap 200,000 2.740 % January 2019 January 2026 Other Liabilities (17,672) $ (46,668) The following table summarizes the notional value at inception and fair value of our joint ventures' derivative financial instruments at March 31, 2021 based on Level 2 information. The notional value is an indication of the extent of our involvement in these instruments at that time, but does not represent exposure to credit, interest rate or market risks (dollars in thousands). Notional Strike Effective Expiration Classification Fair Interest Rate Swap $ 177,000 1.669 % March 2016 February 2026 Liability $ (6,459) Interest Rate Cap 375,000 2.600 % August 2018 September 2021 Asset — Interest Rate Cap 20,026 2.600 % April 2019 September 2021 Asset — Interest Rate Cap 198,000 4.000 % August 2019 August 2022 Asset 2 Interest Rate Cap 220,000 4.000 % February 2020 February 2022 Asset — Interest Rate Cap 550,000 3.750 % August 2020 September 2023 Asset 138 Interest Rate Cap 1,075,000 3.750 % September 2020 September 2021 Asset — Interest Rate Cap 125,000 3.750 % September 2020 September 2021 Asset — Interest Rate Cap 1,250,000 1.250 % November 2020 October 2024 Asset 5,764 Interest Rate Cap 23,000 4.750 % January 2021 January 2023 Asset 1 Interest Rate Swap 2,250,000 1.611 % June 2021 June 2031 Asset 42,635 $ 42,081
Schedule of effect of derivative financial instruments on consolidated statements of income	The following table presents the effect of our derivative financial instruments and our share of our joint ventures' derivative financial instruments that are designated and qualify as hedging instruments on the consolidated statements of operations for the three months ended March 31, 2021 and 2020, respectively (in thousands): Amount of Gain (Loss) Location of Loss Reclassified from Accumulated Other Comprehensive Loss into Income Amount of Loss Reclassified from Three Months Ended March 31, Three Months Ended March 31, Derivative 2021 2020 2021 2020 Interest Rate Swaps/Caps $ 10,220 $ (45,082) Interest expense $ (4,388) $ (725) Share of unconsolidated joint ventures' derivative instruments 34,955 (7,089) Equity in net loss from unconsolidated joint ventures (1,700) (711) $ 45,175 $ (52,171) $ (6,088) $ (1,436)

Lease Income (Tables)

Lease Income (Tables)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Operating Lease, Lease Income	The components of lease income from operating leases during the quarters ended March 31, 2021 and 2020 were as follows (in thousands): Three Months Ended March 31, 2021 2020 Fixed lease payments $ 164,679 $ 194,224 Variable lease payments 25,279 27,168 Total lease payments (1) $ 189,958 $ 221,392 Amortization of acquired above and below-market leases (1,869) 1,239 Total rental revenue $ 188,089 $ 222,631 (1) Amounts include $65.8 million and $66.3 million of sublease income during the three months ended March 31, 2021 and 2020, respectively.
Sales-type Lease, Lease Income	The components of lease income from sales-type leases during the quarters ended March 31, 2021 and 2020 were as follows (in thousands): Three Months Ended March 31, 2021 2020 Interest income (1) $ 1,101 $ — (1) These amounts are included in Other income in our consolidated statements of operations.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of ground lease arrangements	The table below summarizes our current lease arrangements as of March 31, 2021: Property (1) Year of Current Expiration Year of Final Expiration (2) 1185 Avenue of the Americas 2043 2043 SL Green Headquarters at One Vanderbilt (3) 2043 2048 625 Madison Avenue 2022 2054 420 Lexington Avenue 2050 2080 885 Third Avenue 2080 2080 711 Third Avenue (4) 2033 2083 461 Fifth Avenue (5) 2027 2084 1080 Amsterdam Avenue (6) 2111 2111 15 Beekman (7)(8) 2119 2119 (1) All leases are classified as operating leases unless otherwise specified. (2) Reflects exercise of all available extension options. (3) In March 2021, the Company's lease for its corporate headquarters at One Vanderbilt commenced. See note 10, "Related Party Transactions." (4) The Company owns 50% of the fee interest. (5) In April 2021, the Company exercised its option to acquire the fee interest in the property. The transaction is expected to close in the second quarter of 2021 . The lease is classified as a financing lease. (6) A portion of the lease is classified as a financing lease. (7) The Company has an option to purchase the ground lease for a fixed price on a specific date. The lease is classified as a financing lease. (8) In August 2020, the Company entered into a long-term sublease with an unconsolidated joint venture as part of the capitalization of the 15 Beekman development project. See Note 6, "Investments in Unconsolidated Joint Ventures."
Finance lease, liability, maturity	The following is a schedule of future minimum lease payments as evaluated in accordance with ASC 842 for our financing leases and operating leases with initial terms in excess of one year as of March 31, 2021 (in thousands): Financing leases Operating leases Remaining 2021 $ 31,136 $ 31,954 2022 3,522 29,386 2023 3,570 29,502 2024 3,641 30,545 2025 3,810 30,772 2026 3,858 30,911 Thereafter 256,692 631,532 Total minimum lease payments $ 306,229 $ 814,602 Amount representing interest (153,607) Amount discounted using incremental borrowing rate (359,217) Lease liabilities $ 152,622 $ 455,385
Schedule of future minimum rental payments for operating leases	The following is a schedule of future minimum lease payments as evaluated in accordance with ASC 842 for our financing leases and operating leases with initial terms in excess of one year as of March 31, 2021 (in thousands): Financing leases Operating leases Remaining 2021 $ 31,136 $ 31,954 2022 3,522 29,386 2023 3,570 29,502 2024 3,641 30,545 2025 3,810 30,772 2026 3,858 30,911 Thereafter 256,692 631,532 Total minimum lease payments $ 306,229 $ 814,602 Amount representing interest (153,607) Amount discounted using incremental borrowing rate (359,217) Lease liabilities $ 152,622 $ 455,385
Lease, cost	The following table provides lease cost information for the Company's operating leases for the three months ended March 31, 2021 or 2020 (in thousands): Three Months Ended March 31, Operating Lease Costs 2021 2020 Operating lease costs before capitalized operating lease costs $ 7,567 $ 8,113 Operating lease costs capitalized (828) (746) Operating lease costs, net (1) $ 6,739 $ 7,367 (1) This amount is included in operating lease rent in our consolidated statements of operations. The following table provides lease cost information for the Company's financing leases for the three months ended March 31, 2021 or 2020 (in thousands): Three Months Ended March 31, Financing Lease Costs 2021 2020 Interest on financing leases before capitalized interest $ 1,492 $ 1,663 Interest on financing leases capitalized — (747) Interest on financing leases, net (1) 1,492 916 Amortization of right-of-use assets (2) 180 305 Financing lease costs, net $ 1,672 $ 1,221 (1) These amounts are included in interest expense, net of interest income in our consolidated statements of operations. (2) These amounts are included in depreciation and amortization in our consolidated statements of operations.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Schedule of selected results of operations and selected asset information	Selected consolidated results of operations for the three months ended March 31, 2021 and 2020, and selected asset information as of March 31, 2021 and December 31, 2020, regarding our operating segments are as follows (in thousands): Real Estate Segment Debt and Preferred Equity Segment Total Company Total revenues Three months ended: March 31, 2021 $ 206,829 $ 19,273 $ 226,102 March 31, 2020 275,770 38,533 314,303 Net (loss) income Three months ended: March 31, 2021 $ (20,027) $ 16,172 $ (3,855) March 31, 2020 111,233 15,881 127,114 Total assets As of: March 31, 2021 $ 10,896,203 $ 1,147,842 $ 12,044,045 December 31, 2020 10,579,899 1,127,668 11,707,567

Organization and Basis of Pre_3

Organization and Basis of Presentation - Additional Information (Details)	Jan. 15, 2021$ / shares	Jan. 08, 2021	Mar. 31, 2021	Jan. 07, 2021$ / shares	Dec. 31, 2020
Common Stock
Organization
Share price (in dollars per share)				$ 58.15
Reverse stock split conversion ratio		1.02918
Common Stock | Cash Dividend
Organization
Common stock, dividends, per share, cash paid (in dollars per share)	$ 0.3735
Common stock, dividends, per share, stock paid (in dollars per share)	0.0279
Common Stock | Stock Dividend
Organization
Common stock, dividends, per share, stock paid (in dollars per share)	$ 0.0343
Service Corporation
Organization
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent)			95.00%
Operating Partnership | SL Green Operating Partnership
Organization
Noncontrolling interest in the operating partnership (as a percent)			5.65%		5.44%
SL Green Management | SL Green Management LLC
Organization
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent)			100.00%

Organization and Basis of Pre_4

Organization and Basis of Presentation - Schedule of Commercial Office Properties (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)ft²buildingshares
Real estate properties
Number of Buildings | building	65
Approximate Square Feet unaudited (sqft) | ft²	29,134,784
Weighted Average Occupancy unaudited (as a percent)	92.20%
Debt and preferred equity investments including investments held by unconsolidated joint ventures | $	$ 1,100
Debt and preferred equity investments and other financing receivables included in other balance sheet items | $	$ 100
Number of shares to be received on redemption of one unit of limited partnership interests (shares) | shares	1
Commercial properties
Real estate properties
Number of Buildings | building	56
Approximate Square Feet unaudited (sqft) | ft²	27,388,760
Weighted Average Occupancy unaudited (as a percent)	93.00%
Managed office properties
Real estate properties
Number of Buildings | building	2
Approximate Square Feet unaudited (sqft) | ft²	2,100,000
Consolidated properties
Real estate properties
Number of Buildings | building	36
Approximate Square Feet unaudited (sqft) | ft²	13,372,049
Consolidated properties | Commercial properties
Real estate properties
Number of Buildings | building	35
Approximate Square Feet unaudited (sqft) | ft²	13,289,799
Unconsolidated properties
Real estate properties
Number of Buildings | building	29
Approximate Square Feet unaudited (sqft) | ft²	15,762,735
Unconsolidated properties | Commercial properties
Real estate properties
Number of Buildings | building	21
Approximate Square Feet unaudited (sqft) | ft²	14,098,961
Manhattan
Real estate properties
Number of Buildings | building	49
Approximate Square Feet unaudited (sqft) | ft²	26,525,960
Weighted Average Occupancy unaudited (as a percent)	93.50%
Manhattan | Office
Real estate properties
Number of Buildings | building	27
Approximate Square Feet unaudited (sqft) | ft²	21,395,528
Weighted Average Occupancy unaudited (as a percent)	93.40%
Manhattan | Retail
Real estate properties
Number of Buildings | building	10
Approximate Square Feet unaudited (sqft) | ft²	312,036
Weighted Average Occupancy unaudited (as a percent)	94.60%
Manhattan | Development/Redevelopment
Real estate properties
Number of Buildings | building	12
Approximate Square Feet unaudited (sqft) | ft²	4,818,396
Manhattan | Residential
Real estate properties
Number of Buildings | building	9
Approximate Square Feet unaudited (sqft) | ft²	1,746,024
Weighted Average Occupancy unaudited (as a percent)	79.10%
Manhattan | Consolidated properties
Real estate properties
Number of Buildings | building	28
Approximate Square Feet unaudited (sqft) | ft²	12,426,999
Manhattan | Consolidated properties | Office
Real estate properties
Number of Buildings | building	18
Approximate Square Feet unaudited (sqft) | ft²	10,526,345
Manhattan | Consolidated properties | Retail
Real estate properties
Number of Buildings | building	1
Approximate Square Feet unaudited (sqft) | ft²	10,040
Manhattan | Consolidated properties | Development/Redevelopment
Real estate properties
Number of Buildings | building	9
Approximate Square Feet unaudited (sqft) | ft²	1,890,614
Manhattan | Consolidated properties | Residential
Real estate properties
Number of Buildings | building	1
Approximate Square Feet unaudited (sqft) | ft²	82,250
Manhattan | Unconsolidated properties
Real estate properties
Number of Buildings | building	21
Approximate Square Feet unaudited (sqft) | ft²	14,098,961
Manhattan | Unconsolidated properties | Office
Real estate properties
Number of Buildings | building	9
Approximate Square Feet unaudited (sqft) | ft²	10,869,183
Manhattan | Unconsolidated properties | Retail
Real estate properties
Number of Buildings | building	9
Approximate Square Feet unaudited (sqft) | ft²	301,996
Manhattan | Unconsolidated properties | Development/Redevelopment
Real estate properties
Number of Buildings | building	3
Approximate Square Feet unaudited (sqft) | ft²	2,927,782
Manhattan | Unconsolidated properties | Residential
Real estate properties
Number of Buildings | building	8
Approximate Square Feet unaudited (sqft) | ft²	1,663,774
Suburban | Office
Real estate properties
Number of Buildings | building	7
Approximate Square Feet unaudited (sqft) | ft²	862,800
Weighted Average Occupancy unaudited (as a percent)	81.60%
Suburban | Consolidated properties | Office
Real estate properties
Number of Buildings | building	7
Approximate Square Feet unaudited (sqft) | ft²	862,800
Suburban | Unconsolidated properties | Office
Real estate properties
Number of Buildings | building	0
Approximate Square Feet unaudited (sqft) | ft²	0

Organization and Basis of Pre_5

Organization and Basis of Presentation - Subsequent Events (Details) $ in Millions	1 Months Ended
	Apr. 30, 2021USD ($)
Subsequent Event | 461 Fifth Avenue
Subsequent Event [Line Items]
Payments to acquire real estate	$ 28

Significant Accounting Polici_4

Significant Accounting Policies - Investments in Commercial Real Estate Properties (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Investment in Commercial Real Estate Properties
Rental revenue from amortization of acquired leases	$ 1,900,000	$ 1,200,000
Identified intangible assets (included in other assets):
Gross amount	239,562,000		$ 215,673,000
Accumulated amortization	(204,386,000)		(190,523,000)
Net	35,176,000		25,150,000
Identified intangible liabilities (included in deferred revenue):
Gross amount	242,334,000		241,409,000
Accumulated amortization	(233,766,000)		(230,479,000)
Net	8,568,000		10,930,000
Net intangible assets reclassified to assets held for sale	0		0
Net intangible liabilities reclassified to liabilities relates to assets held for sale	$ 0		$ 0
Minimum | Above-market leases
Investment in Commercial Real Estate Properties
Estimated useful life of other intangible assets (in years)	1 year
Minimum | Below-market leases
Investment in Commercial Real Estate Properties
Estimated useful life of other intangible assets (in years)	1 year
Minimum | In-place leases
Investment in Commercial Real Estate Properties
Estimated useful life of other intangible assets (in years)	1 year
Maximum | Above-market leases
Investment in Commercial Real Estate Properties
Estimated useful life of other intangible assets (in years)	15 years
Maximum | Below-market leases
Investment in Commercial Real Estate Properties
Estimated useful life of other intangible assets (in years)	15 years
Maximum | In-place leases
Investment in Commercial Real Estate Properties
Estimated useful life of other intangible assets (in years)	15 years
Building | Minimum
Investment in Commercial Real Estate Properties
Estimated useful life (in years)	3 years
Building | Maximum
Investment in Commercial Real Estate Properties
Estimated useful life (in years)	40 years

Significant Accounting Polici_5

Significant Accounting Policies - Investment in Marketable Securities (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)security	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Investment in Marketable Securities
Marketable securities	$ 23,784,000		$ 28,570,000
Equity marketable securities	23,784,000		28,570,000
Proceeds from sale of marketable securities	$ 5,000,000	$ 0
Number of marketable securities sold | security	1
Fair Value
Investment in Marketable Securities
Marketable securities	$ 23,784,000		28,570,000
Equity marketable securities
Investment in Marketable Securities
Equity marketable securities	0		0
Commercial mortgage-backed securities
Investment in Marketable Securities
Marketable securities	23,784,000		28,570,000
Cost basis of commercial mortgage-backed securities	$ 23,000,000		27,500,000
Number of securities in continuous unrealized loss position | security	1
Unrealized loss	$ 700,000		700,000
Fair value of security in a continuous unrealized loss position for less than 12 months	$ 7,100,000		$ 7,000,000

Significant Accounting Polici_6

Significant Accounting Policies - Revenue Recognition/Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income taxes
Federal, state and local tax provision	$ 0.7	$ 1.1

Significant Accounting Polici_7

Significant Accounting Policies - Concentrations of Credit Risk/Accounting Standards Updates (Details) - Annualized rent - Customer concentration	3 Months Ended
	Mar. 31, 2021Tenant
Concentration of Credit Risk
Number of tenants (tenants)	1
Maximum percentage of annualized rent for any one tenant not individually disclosed (percent) (more than)	5.00%
11 Madison Avenue
Concentration of Credit Risk
Percentage of concentration (percent)	9.20%
420 Lexington Avenue
Concentration of Credit Risk
Percentage of concentration (percent)	7.20%
1185 Avenue of the Americas
Concentration of Credit Risk
Percentage of concentration (percent)	7.10%
1515 Broadway
Concentration of Credit Risk
Percentage of concentration (percent)	6.90%
220 East 42nd Street
Concentration of Credit Risk
Percentage of concentration (percent)	6.20%
280 Park Avenue
Concentration of Credit Risk
Percentage of concentration (percent)	5.80%
485 Lexington Avenue
Concentration of Credit Risk
Percentage of concentration (percent)	5.10%
Tenant 1
Concentration of Credit Risk
Percentage of concentration (percent)	5.90%

Property Acquisitions (Details)

Property Acquisitions (Details) $ in Millions	Mar. 31, 2021ft²	Jan. 31, 2021USD ($)ft²
Property Acquisitions
Area of Real Estate Property	29,134,784
885 Third Avenue
Property Acquisitions
Area of Real Estate Property		625,000
Gross Asset Valuation (in millions) | $		$ 387.9

Properties Held for Sale and _3

Properties Held for Sale and Property Dispositions (Details) $ in Millions	1 Months Ended
	Mar. 31, 2021USD ($)ft²	Feb. 28, 2021USD ($)ft²	Jan. 31, 2021USD ($)ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Real Estate Property | ft²	29,134,784
712 Madison Avenue
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Real Estate Property | ft²			6,600
Sales Price			$ 43
Gain (loss)			$ (1.4)
133 Greene Street
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Real Estate Property | ft²		6,425
Sales Price		$ 15.8
Gain (loss)		$ 0.2
106 Spring Street (2)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of Real Estate Property | ft²	5,928
Sales Price	$ 35
Gain (loss)	$ (2.8)

Debt and Preferred Equity Inv_3

Debt and Preferred Equity Investments - Rollforward of Net Book Balance (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance at beginning of period	$ 1,076,542	$ 1,580,306
Redemptions/Sales/Syndications/Equity Ownership/Amortization	0	(1,048,643)
Net change in loan loss reserves	0	(11,463)
Balance at end of period	1,097,202	1,076,542
Debt Investments in Mortgage Loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Originations/Accretion	17,465	389,300
Preferred equity investments
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Originations/Accretion	$ 3,195	$ 167,042

Debt and Preferred Equity Inv_4

Debt and Preferred Equity Investments - Debt and Preferred Equity Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Carrying Value	$ 1,097,202	$ 1,076,542
Senior Financing	6,565,960
Total floating rate
Debt Instrument [Line Items]
Carrying Value	352,650
Face Value	361,828
Total fixed rate
Debt Instrument [Line Items]
Carrying Value	744,552
Face Value	758,404
Senior Mortgage Debt
Debt Instrument [Line Items]
Carrying Value	65,291
Senior Financing	$ 0
Weighted Average Yield at End of Period	4.74%
Senior Mortgage Debt | Total floating rate
Debt Instrument [Line Items]
Carrying Value	$ 64,042
Face Value	64,649
Senior Mortgage Debt | Total fixed rate
Debt Instrument [Line Items]
Carrying Value	1,249
Face Value	1,250
Junior Mortgage Debt
Debt Instrument [Line Items]
Carrying Value	50,026
Senior Financing	$ 127,000
Weighted Average Yield at End of Period	7.82%
Junior Mortgage Debt | Total floating rate
Debt Instrument [Line Items]
Carrying Value	$ 7,207
Face Value	12,000
Junior Mortgage Debt | Total fixed rate
Debt Instrument [Line Items]
Carrying Value	42,819
Face Value	43,000
Mezzanine Debt
Debt Instrument [Line Items]
Carrying Value	718,904
Senior Financing	$ 4,476,210
Weighted Average Yield at End of Period	5.86%
Mezzanine Debt | Total floating rate
Debt Instrument [Line Items]
Carrying Value	$ 281,401
Face Value	285,179
Mezzanine Debt | Total fixed rate
Debt Instrument [Line Items]
Carrying Value	437,503
Face Value	449,102
Preferred Equity
Debt Instrument [Line Items]
Carrying Value	262,981
Senior Financing	$ 1,962,750
Weighted Average Yield at End of Period	9.94%
Preferred Equity | Total floating rate
Debt Instrument [Line Items]
Carrying Value	$ 0
Face Value	0
Preferred Equity | Total fixed rate
Debt Instrument [Line Items]
Carrying Value	262,981
Face Value	$ 265,052
Minimum | Senior Mortgage Debt | Total fixed rate
Debt Instrument [Line Items]
Interest rate	3.50%
Minimum | Junior Mortgage Debt | Total fixed rate
Debt Instrument [Line Items]
Interest rate	6.25%
Minimum | Mezzanine Debt | Total fixed rate
Debt Instrument [Line Items]
Interest rate	2.90%
Minimum | Preferred Equity | Total fixed rate
Debt Instrument [Line Items]
Interest rate	6.50%
Maximum | Mezzanine Debt | Total fixed rate
Debt Instrument [Line Items]
Interest rate	14.30%
Maximum | Preferred Equity | Total fixed rate
Debt Instrument [Line Items]
Interest rate	11.00%
LIBOR | Minimum | Senior Mortgage Debt | Total floating rate
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
LIBOR | Minimum | Junior Mortgage Debt | Total floating rate
Debt Instrument [Line Items]
Basis spread on variable rate	7.25%
LIBOR | Minimum | Mezzanine Debt | Total floating rate
Debt Instrument [Line Items]
Basis spread on variable rate	4.95%
LIBOR | Maximum | Senior Mortgage Debt | Total floating rate
Debt Instrument [Line Items]
Basis spread on variable rate	3.50%
LIBOR | Maximum | Mezzanine Debt | Total floating rate
Debt Instrument [Line Items]
Basis spread on variable rate	13.61%

Debt and Preferred Equity Inv_5

Debt and Preferred Equity Investments - Rollforward of Total Allowance for Loan Loss Reserves (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)loan	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Loan loss reserve activity
Balance at beginning of year	$ 13,213	$ 1,750	$ 1,750
Current period provision for loan loss	0	2,800	20,693
Write-offs charged against the allowance	0		(37,033)
Balance at end of period	$ 13,213		13,213
Number of financing receivables on non-accrual without allowance for loan loss | loan	1
Financing receivable on non-accrual without allowance	$ 225,400
Investments Sold In 2020
Loan loss reserve activity
Write-offs charged against the allowance			(19,000)
Cumulative Effect, Period of Adoption, Adjustment
Loan loss reserve activity
Balance at beginning of year	$ 0	$ 27,803	27,803
Balance at end of period			$ 0

Debt and Preferred Equity Inv_6

Debt and Preferred Equity Investments - Investment In Financing Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value	$ 1,097,202	$ 1,076,542
2020	0
2019	361,444
2018	297,924
Prior	437,834
1 - Low Risk Assets - Low probability of loss
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value	712,994	695,035
2020	0
2019	361,444
2018	56,639
Prior	294,911
2 - Watch List Assets - Higher potential for loss
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value	367,859	365,167
2020	0
2019	0
2018	241,285
Prior	126,574
3 - High Risk Assets - Loss more likely than not
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value	16,349	$ 16,340
2020	0
2019	0
2018	0
Prior	$ 16,349

Debt and Preferred Equity Inv_7

Debt and Preferred Equity Investments - Debt Investment (Details) - USD ($)	1 Months Ended	3 Months Ended
	Apr. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Aggregate weighted average current yield (as a percent)		5.90%
Debt Investments Held [Abstract]
Carrying Value		$ 1,097,202,000	$ 1,076,542,000
Carrying Value		1,097,202,000	1,076,542,000
Junior Mortgage Due July 2021
Debt Investments Held [Abstract]
Amount participated out		66,600,000
Mezzanine Loan With Maturity June 2023
Debt Investments Held [Abstract]
Loan interest income		0
Mezzanine Loan with an Initial Maturity Date of June 2024
Debt Investments Held [Abstract]
Amount participated out		12,000,000
Loan interest income		0
Mezzanine Loan Due March 2022
Debt Investments Held [Abstract]
Amount participated out		400,000
Debt Investments in Mortgage Loans
Debt Investments Held [Abstract]
Future Funding Obligations		106,935,000
Senior Financing		4,543,210,000
Allowance for loan loss		(13,213,000)	(13,213,000)
Carrying Value		834,221,000	816,756,000
Total fixed rate
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		2,782,737,000
Carrying Value		488,201,000	477,509,000
Total fixed rate | Junior Mortgage Due July 2021
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		67,000,000
Carrying Value		42,820,000	32,888,000
Total fixed rate | Mezzanine Loan, September 2021
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		15,000,000
Carrying Value		3,500,000	3,500,000
Total fixed rate | Mortgage/Mezzanine Loan Due October 2021
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		63,750,000
Carrying Value		56,246,000	56,244,000
Total fixed rate | Mezzanine Loan With An Initial Maturity Of August 2022
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		280,000,000
Carrying Value		41,652,000	41,057,000
Total fixed rate | Mezzanine Loan With Maturity June 2023
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		359,237,000
Carrying Value		225,367,000	225,204,000
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of June 2024
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		105,000,000
Carrying Value		13,366,000	13,366,000
Total fixed rate | Mezzanine Loan, with an Initial Maturity Date of January 2025
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		95,000,000
Carrying Value		30,000,000	30,000,000
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of June 2027
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		1,712,750,000
Carrying Value		55,250,000	55,250,000
Total fixed rate | Mezzanine Loan With Initial Maturity Date Of December 2029
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		85,000,000
Carrying Value		20,000,000	20,000,000
Total floating rate
Debt Investments Held [Abstract]
Future Funding Obligations		106,935,000
Senior Financing		1,760,473,000
Carrying Value		359,233,000	352,460,000
Total floating rate | Mezzanine Loan Due April 2021
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		275,000,000
Carrying Value		49,992,000	49,956,000
Total floating rate | Junior Mortgage Participation/Mezzanine Loan Due July 2021
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		60,000,000
Carrying Value		15,742,000	15,733,000
Total floating rate | Mezzanine Loan Due July 2021
Debt Investments Held [Abstract]
Future Funding Obligations		5,761,000
Senior Financing		177,415,000
Carrying Value		36,639,000	35,318,000
Total floating rate | Mezzanine Loan Due July 2021, 2
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		61,744,000
Carrying Value		29,130,000	29,106,000
Total floating rate | Mezzanine Loan Due March 2022
Debt Investments Held [Abstract]
Future Funding Obligations		0
Senior Financing		1,115,000,000
Carrying Value		129,330,000	127,915,000
Total floating rate | Mezzanine Loan Due April 2022 | Subsequent Event
Debt Investments Held [Abstract]
Extension term	1 year
Total floating rate | Mortgage/Mezzanine Loan Due May 2022
Debt Investments Held [Abstract]
Future Funding Obligations		6,769,000
Senior Financing		0
Carrying Value		60,922,000	60,532,000
Total floating rate | Mezzanine Loan Due December 2022
Debt Investments Held [Abstract]
Future Funding Obligations		42,117,000
Senior Financing		0
Carrying Value		15,918,000	14,011,000
Total floating rate | Mezzanine Loan Due May 2023
Debt Investments Held [Abstract]
Future Funding Obligations		52,288,000
Senior Financing		71,314,000
Carrying Value		$ 21,560,000	$ 19,889,000

Debt and Preferred Equity Inv_8

Debt and Preferred Equity Investments - Preferred Equity Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Preferred equity investment
Aggregate weighted average current yield (as a percent)	5.90%
Carrying Value	$ 1,097,202	$ 1,076,542
Preferred Equity, June 2022
Preferred equity investment
Future Funding Obligations	0
Senior Financing	1,712,750
Carrying Value	156,169	154,691
Preferred Equity, February 2027
Preferred equity investment
Future Funding Obligations	0
Senior Financing	250,000
Carrying Value	$ 106,812	105,095
Preferred equity investments
Preferred equity investment
Aggregate weighted average current yield (as a percent)	9.94%
Future Funding Obligations	$ 0
Senior Financing	1,962,750
Carrying Value	262,981	259,786
Allowance for loan loss	0	0
Total after allowance for loan loss	$ 262,981	$ 259,786

Debt and Preferred Equity Inv_9

Debt and Preferred Equity Investments - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)segmentinvestment	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)
Preferred equity investment
Number of investments, nonperforming | investment	1
Carrying Value	$ 1,097,202,000		$ 1,076,542,000
Recorded investment, nonaccrual status	$ 27,700,000
Number of portfolio segments of financial receivables (segment) | segment	1		1
Additional amount of financing receivables included in other assets	$ 66,400,000		$ 66,200,000
Current period provision for loan loss	0	$ 2,800,000	20,693,000
Allowance for loan and lease losses, real estate	13,213,000		13,213,000	$ 1,750,000
3 - High Risk Assets - Loss more likely than not
Preferred equity investment
Recorded investment, nonaccrual status	2,500,000
Financing Receivables, Equal to Greater than 90 Days Past Due
Preferred equity investment
Recorded investment, past due	0		0
Cumulative Effect, Period of Adoption, Adjustment
Preferred equity investment
Allowance for loan and lease losses, real estate			0	$ 27,803,000
Total floating rate
Preferred equity investment
Carrying Value	359,233,000		$ 352,460,000
Total floating rate | Mortgage/Mezzanine Loan Due March 2020
Preferred equity investment
Carrying Value	$ 6,800,000

Investments in Unconsolidated_3

Investments in Unconsolidated Joint Ventures - Additional Information (Details) $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Apr. 30, 2021USD ($)	Oct. 31, 2016	Mar. 31, 2021USD ($)ft²unitpartner	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
General information on each joint venture
Equity method investments | $			$ 3,698,701		$ 3,823,322
Net equity investment in VIEs in which the entity is not primary beneficiary | $			$ 132,700		$ 134,000
Unaudited Approximate Square Feet (sqft)			29,134,784
(Loss) gain on sale of real estate, net | $			$ (1,388)	$ 72,636
One Madison Avenue
General information on each joint venture
Ownership percentage deconsolidated					50.50%
Investment fair value adjustment | $			$ 2,700		$ 187,500
Stonehenge Portfolio
General information on each joint venture
Ownership Interest Disposed		90.00%
East 400 Street 57
General information on each joint venture
Ownership Interest Disposed		51.00%
One Madison Avenue
General information on each joint venture
Investment in joint venture aggregate equity committed by partner | $					$ 492,200
Investment in joint venture aggregate maximum ownership percentage					49.50%
Investment in joint venture, number of partners | partner			2
Investment in joint venture, ownership percentage			9.00%
East 400 Street 57
General information on each joint venture
Ownership percentage in disposed asset		49.00%
East 400 Street 57 | Subsequent Event
General information on each joint venture
Asset impairment charges | $	$ 5,700
21 East 66th Street | Three Retail and Two Residential Units
General information on each joint venture
Ownership Interest Disposed			32.28%
Number of stores | unit			3
Number of residential units | unit			1
21 East 66th Street | Three Residential Units
General information on each joint venture
Ownership Interest Disposed			16.14%
Number of residential units | unit			3
Joint venture
General information on each joint venture
Equity method investments | $			$ 3,698,701
Equity method investments with negative book value | $			$ 92,400
Joint venture | 100 Park Avenue
General information on each joint venture
Ownership Interest Disposed			49.90%
Economic Interest (as a percent)			49.90%
Unaudited Approximate Square Feet (sqft)			834,000
Joint venture | 717 Fifth Avenue
General information on each joint venture
Ownership Interest Disposed			10.92%
Economic Interest (as a percent)			10.92%
Unaudited Approximate Square Feet (sqft)			119,500
Joint venture | 800 Third Avenue
General information on each joint venture
Ownership Interest Disposed			60.52%
Economic Interest (as a percent)			60.52%
Unaudited Approximate Square Feet (sqft)			526,000
Interest rate, fixed rate debt (as a percent)			3.37%
Joint venture | 919 Third Avenue
General information on each joint venture
Ownership Interest Disposed			51.00%
Economic Interest (as a percent)			51.00%
Unaudited Approximate Square Feet (sqft)			1,454,000
Interest rate, fixed rate debt (as a percent)			5.12%
Joint venture | 11 West 34th Street
General information on each joint venture
Ownership Interest Disposed			30.00%
Economic Interest (as a percent)			30.00%
Unaudited Approximate Square Feet (sqft)			17,150
Joint venture | 280 Park Avenue
General information on each joint venture
Ownership Interest Disposed			50.00%
Economic Interest (as a percent)			50.00%
Unaudited Approximate Square Feet (sqft)			1,219,158
Joint venture | 1552-1560 Broadway
General information on each joint venture
Ownership Interest Disposed			50.00%
Economic Interest (as a percent)			50.00%
Unaudited Approximate Square Feet (sqft)			57,718
Joint venture | 10 East 53rd Street
General information on each joint venture
Ownership Interest Disposed			55.00%
Economic Interest (as a percent)			55.00%
Unaudited Approximate Square Feet (sqft)			354,300
Joint venture | 21 East 66th Street
General information on each joint venture
Ownership Interest Disposed			32.28%
Economic Interest (as a percent)			32.28%
Unaudited Approximate Square Feet (sqft)			13,069
Interest rate, fixed rate debt (as a percent)			3.60%
Joint venture | 650 Fifth Avenue
General information on each joint venture
Ownership Interest Disposed			50.00%
Economic Interest (as a percent)			50.00%
Unaudited Approximate Square Feet (sqft)			69,214
Joint venture | 121 Greene Street
General information on each joint venture
Ownership Interest Disposed			50.00%
Economic Interest (as a percent)			50.00%
Unaudited Approximate Square Feet (sqft)			7,131
Joint venture | Stonehenge Portfolio
General information on each joint venture
Ownership Interest Disposed		10.00%
Unaudited Approximate Square Feet (sqft)			1,439,016
Interest rate, fixed rate debt (as a percent)			3.50%
Joint venture | 605 West 42nd Street
General information on each joint venture
Ownership Interest Disposed			20.00%
Economic Interest (as a percent)			20.00%
Unaudited Approximate Square Feet (sqft)			927,358
Joint venture | 11 Madison Avenue
General information on each joint venture
Ownership Interest Disposed			60.00%
Economic Interest (as a percent)			60.00%
Unaudited Approximate Square Feet (sqft)			2,314,000
Interest rate, fixed rate debt (as a percent)			3.84%
Joint venture | East 400 Street 57
General information on each joint venture
Ownership Interest Disposed			51.00%
Economic Interest (as a percent)			41.00%
Unaudited Approximate Square Feet (sqft)			290,482
Interest rate, fixed rate debt (as a percent)			3.00%
Joint venture | One Vanderbilt
General information on each joint venture
Ownership Interest Disposed			71.01%
Economic Interest (as a percent)			71.01%
Unaudited Approximate Square Feet (sqft)			1,657,198
Joint venture | Worldwide Plaza
General information on each joint venture
Ownership Interest Disposed			24.35%
Economic Interest (as a percent)			24.35%
Unaudited Approximate Square Feet (sqft)			2,048,725
Interest rate, fixed rate debt (as a percent)			3.98%
Joint venture | 1515 Broadway
General information on each joint venture
Ownership Interest Disposed			56.87%
Economic Interest (as a percent)			56.87%
Unaudited Approximate Square Feet (sqft)			1,750,000
Interest rate, fixed rate debt (as a percent)			3.93%
Joint venture | 2 Herald Square
General information on each joint venture
Ownership Interest Disposed			51.00%
Economic Interest (as a percent)			51.00%
Unaudited Approximate Square Feet (sqft)			369,000
Joint venture | 115 Spring Street
General information on each joint venture
Ownership Interest Disposed			51.00%
Economic Interest (as a percent)			51.00%
Unaudited Approximate Square Feet (sqft)			5,218
Joint venture | 15 Beekman
General information on each joint venture
Ownership Interest Disposed			20.00%
Economic Interest (as a percent)			20.00%
Unaudited Approximate Square Feet (sqft)			221,884
Joint venture | 85 Fifth Avenue
General information on each joint venture
Ownership Interest Disposed			36.30%
Economic Interest (as a percent)			36.30%
Unaudited Approximate Square Feet (sqft)			12,946
Joint venture | One Madison Avenue
General information on each joint venture
Ownership Interest Disposed			50.50%
Economic Interest (as a percent)			50.50%
Unaudited Approximate Square Feet (sqft)			1,048,700

Investments in Unconsolidated_4

Investments in Unconsolidated Joint Ventures - Acquisition, Development and Construction Arrangements/Sale of Joint Venture Interest or Property (Details) - USD ($)	1 Months Ended	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2021	Mar. 31, 2020
Schedule of Equity Method Investments [Line Items]
Equity in net (loss) gain on sale of interest in unconsolidated joint venture/real estate		$ (12,629,000)	$ 0
55 West 46th Street, Tower 46 | Joint venture
Schedule of Equity Method Investments [Line Items]
Ownership Interest Disposed	25.00%	25.00%
Gross Asset Valuation	$ 275,000	$ 275,000
Equity in net (loss) gain on sale of interest in unconsolidated joint venture/real estate	$ (15,200)

Investments in Unconsolidated_5

Investments in Unconsolidated Joint Ventures - Mortgages and Other Loans Payable (Details)	1 Months Ended	3 Months Ended
	Mar. 31, 2021USD ($)partnermortgage	Mar. 31, 2021USD ($)extensionmortgagepartner	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Total fixed rate debt	$ 1,081,142,000	$ 1,081,142,000	$ 1,083,683,000
Total floating rate debt	786,521,000	786,521,000	917,677,000
Revolving credit facility, net	625,809,000	625,809,000	105,262,000
Joint venture
Debt Instrument [Line Items]
Total fixed rate debt	5,328,127,000	5,328,127,000	5,604,858,000
Total floating rate debt	4,185,048,000	4,185,048,000	4,257,792,000
Total fixed rate and floating rate debt	9,513,175,000	9,513,175,000	9,862,650,000
Deferred financing costs, net	(98,252,000)	(98,252,000)	(113,446,000)
Total joint venture mortgages and other loans payable, net	$ 9,414,923,000	$ 9,414,923,000	9,749,204,000
Joint venture | 717 Fifth Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	10.92%	10.92%
Joint venture | 717 Fifth Avenue | Mortgage loan
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.45%	4.45%
Total fixed rate debt	$ 300,000,000	$ 300,000,000	300,000,000
Joint venture | 717 Fifth Avenue | Mezzanine loans
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	5.50%	5.50%
Total fixed rate debt	$ 355,328,000	$ 355,328,000	355,328,000
Joint venture | 650 Fifth Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.00%	50.00%
Joint venture | 650 Fifth Avenue | Mortgage loan
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.46%	4.46%
Total fixed rate debt	$ 210,000,000	$ 210,000,000	210,000,000
Joint venture | 650 Fifth Avenue | Mezzanine loans
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	5.45%	5.45%
Total fixed rate debt	$ 65,000,000	$ 65,000,000	65,000,000
Joint venture | East 21 Street 66 [Member]
Debt Instrument [Line Items]
Economic Interest (as a percent)	32.28%	32.28%
Interest rate, fixed rate debt (as a percent)	3.60%	3.60%
Interest rate, floating rate debt (as a percent)	2.75%	2.75%
Total fixed rate debt	$ 12,000,000	$ 12,000,000	12,000,000
Total floating rate debt	$ 666,000	$ 666,000	677,000
Joint venture | 919 Third Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	51.00%	51.00%
Interest rate, fixed rate debt (as a percent)	5.12%	5.12%
Total fixed rate debt	$ 500,000,000	$ 500,000,000	500,000,000
Joint venture | 1515 Broadway
Debt Instrument [Line Items]
Economic Interest (as a percent)	56.87%	56.87%
Interest rate, fixed rate debt (as a percent)	3.93%	3.93%
Total fixed rate debt	$ 815,876,000	$ 815,876,000	820,607,000
Joint venture | 11 Madison Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	60.00%	60.00%
Interest rate, fixed rate debt (as a percent)	3.84%	3.84%
Total fixed rate debt	$ 1,400,000,000	$ 1,400,000,000	1,400,000,000
Joint venture | 800 Third Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	60.52%	60.52%
Interest rate, fixed rate debt (as a percent)	3.37%	3.37%
Total fixed rate debt	$ 177,000,000	$ 177,000,000	177,000,000
Joint venture | East 400 Street 57
Debt Instrument [Line Items]
Economic Interest (as a percent)	41.00%	41.00%
Interest rate, fixed rate debt (as a percent)	3.00%	3.00%
Total fixed rate debt	$ 97,024,000	$ 97,024,000	97,024,000
Joint venture | Worldwide Plaza
Debt Instrument [Line Items]
Economic Interest (as a percent)	24.35%	24.35%
Interest rate, fixed rate debt (as a percent)	3.98%	3.98%
Total fixed rate debt	$ 1,200,000,000	$ 1,200,000,000	1,200,000,000
Joint venture | Stonehenge Portfolio
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.50%	3.50%
Total fixed rate debt	$ 195,899,000	$ 195,899,000	195,899,000
Joint venture | 885 Third Avenue
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)
Total fixed rate debt	$ 0	$ 0	272,000,000
Joint venture | 121 Greene Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.00%	50.00%
Interest rate, floating rate debt (as a percent)	2.00%	2.00%
Total floating rate debt	$ 13,771,000	$ 13,771,000	15,000,000
Period of extension options	1 year
Joint venture | 280 Park Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.00%	50.00%
Interest rate, floating rate debt (as a percent)	1.73%	1.73%
Total floating rate debt	$ 1,200,000,000	$ 1,200,000,000	1,200,000,000
Joint venture | One Vanderbilt
Debt Instrument [Line Items]
Economic Interest (as a percent)	71.01%	71.01%
Interest rate, floating rate debt (as a percent)	2.50%	2.50%
Total floating rate debt	$ 1,283,292,000	$ 1,283,292,000	1,210,329,000
Joint venture | One Vanderbilt | Construction Loans
Debt Instrument [Line Items]
Maximum facility capacity	$ 1,750,000,000	$ 1,750,000,000
Term (in Years)		3 years
Number of extension options | extension		2
Period of extension options		1 year
Joint venture | 1552 Broadway
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.00%	50.00%
Interest rate, floating rate debt (as a percent)	2.65%	2.65%
Total floating rate debt	$ 195,000,000	$ 195,000,000	195,000,000
Joint venture | 2 Herald Square
Debt Instrument [Line Items]
Economic Interest (as a percent)	51.00%	51.00%
Interest rate, floating rate debt (as a percent)	1.45%	1.45%
Total floating rate debt	$ 214,500,000	$ 214,500,000	214,500,000
Joint venture | 11 West 34th Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	30.00%	30.00%
Interest rate, floating rate debt (as a percent)	1.45%	1.45%
Total floating rate debt	$ 23,000,000	$ 23,000,000	23,000,000
Joint venture | 115 Spring Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	51.00%	51.00%
Interest rate, floating rate debt (as a percent)	3.40%	3.40%
Total floating rate debt	$ 65,550,000	$ 65,550,000	65,550,000
Joint venture | 100 Park Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	49.90%	49.90%
Interest rate, floating rate debt (as a percent)	2.25%	2.25%
Total floating rate debt	$ 360,000,000	$ 360,000,000	360,000,000
Joint venture | 15 Beekman
Debt Instrument [Line Items]
Economic Interest (as a percent)	20.00%	20.00%
Interest rate, floating rate debt (as a percent)	1.50%	1.50%
Total floating rate debt	$ 19,165,000	$ 19,165,000	11,212,000
Joint venture | 15 Beekman | Construction Loans
Debt Instrument [Line Items]
Maximum facility capacity	$ 125,000,000	$ 125,000,000
Joint venture | 10 East 53rd Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	55.00%	55.00%
Interest rate, floating rate debt (as a percent)	1.35%	1.35%
Total floating rate debt	$ 220,000,000	$ 220,000,000	220,000,000
Joint venture | One Madison Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.50%	50.50%
Interest rate, floating rate debt (as a percent)	3.35%	3.35%
Total floating rate debt	$ 40,104,000	$ 40,104,000	0
Joint venture | One Madison Avenue | Construction Loans
Debt Instrument [Line Items]
Maximum facility capacity	$ 1,250,000,000	$ 1,250,000,000
Term (in Years)		5 years
Number of extension options | extension		1
Period of extension options		1 year
Joint venture | 605 West 42nd Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	20.00%	20.00%
Interest rate, floating rate debt (as a percent)	1.44%	1.44%
Total floating rate debt	$ 550,000,000	$ 550,000,000	550,000,000
Joint venture | 55 West 46th Street
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)
Total floating rate debt	$ 0	$ 0	$ 192,524,000
Secured Debt, Initial Maturity April 2028 | Joint venture | Stonehenge Portfolio
Debt Instrument [Line Items]
Total fixed rate debt	$ 132,400,000	$ 132,400,000
Number of mortgages | partner	3	3
Secured Debt, Initial Maturity July 2029 | Joint venture | Stonehenge Portfolio
Debt Instrument [Line Items]
Total fixed rate debt	$ 63,500,000	$ 63,500,000
Number of mortgages | mortgage	2	2

Investments in Unconsolidated_6

Investments in Unconsolidated Joint Ventures - Schedules of Combined Financial Statements for the Unconsolidated Joint Ventures (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Assets
Commercial real estate property, net		$ 5,825,629		$ 5,399,002
Cash and restricted cash		304,999	$ 554,195	266,059
Tenant and other receivables, related party receivables, and deferred rents receivable		42,505		44,507
Other assets		445,635		448,213
Total assets	[1]	12,044,045		11,707,567
Liabilities and equity
Mortgages and other loans payable, net		1,848,701		1,979,972
Lease liabilities		455,385		339,458
Other liabilities		267,908		302,798
Equity		4,935,620	5,343,965	4,935,795	$ 5,517,198
Total liabilities and equity/capital		12,044,045		11,707,567
Company's investments in unconsolidated joint ventures		3,698,701		3,823,322
Investments difference between carrying amount and underlying equity		174,200
Combined statements of income for the unconsolidated joint ventures
Total revenues		226,102	314,303
Operating expenses		42,284	53,866
Real estate taxes		45,411	46,622
Interest expense before capitalized interest		39,868	56,813
Amortization of deferred financing costs		3,774	2,500
Depreciation and amortization		62,996	68,279
Total expenses		207,499	247,011
Net (loss) income		(3,855)	127,114
Company's equity in net (loss) income from unconsolidated joint ventures		(2,864)	(12,814)
Joint venture
Assets
Commercial real estate property, net		15,243,331		16,143,880
Cash and restricted cash		317,753		357,076
Tenant and other receivables, related party receivables, and deferred rents receivable		412,203		403,883
Other assets		1,950,444		2,001,612
Total assets		17,923,731		18,906,451
Liabilities and equity
Mortgages and other loans payable, net		9,414,923		9,749,204
Deferred revenue		1,311,191		1,341,571
Lease liabilities		985,622		1,002,563
Other liabilities		373,400		464,107
Equity		5,838,595		6,349,006
Total liabilities and equity/capital		17,923,731		$ 18,906,451
Company's investments in unconsolidated joint ventures		3,698,701
Combined statements of income for the unconsolidated joint ventures
Total revenues		301,541	282,520
Operating expenses		46,233	51,590
Real estate taxes		54,592	53,372
Operating lease, rent		5,644	6,361
Interest expense before capitalized interest		78,749	86,324
Amortization of deferred financing costs		6,384	4,814
Depreciation and amortization		114,879	98,584
Total expenses		306,481	301,045
Net (loss) income		(4,940)	(18,525)
Company's equity in net (loss) income from unconsolidated joint ventures		(2,864)	(12,814)
Management Service, Base | Joint venture
Investment in Unconsolidated Joint Ventures
Management fees, base revenue		$ 2,400	$ 2,200
[1]	The Company's consolidated balance sheets include assets and liabilities of consolidated variable interest entities ("VIEs"). See Note 2. The consolidated balance sheets include the following amounts related to our consolidated VIEs, excluding the Operating Partnership: $179.6 million and $41.2 million of land, $282.3 million and $57.9 million of building and improvements, $2.0 million and $2.0 million of building and leasehold improvements, $53.2 million and $37.8 million of right of use assets, $16.4 million and $10.3 million of accumulated depreciation, $297.1 million and $289.5 million of other assets included in other line items, $368.6 million and $94.0 million of real estate debt, net, $0.9 million and $0.7 million of accrued interest payable, $45.3 million and $29.9 million of lease liabilities, and $31.2 million and $56.6 million of other liabilities included in other line items as of March 31, 2021 and December 31, 2020, respectively.

Deferred Costs (Details)

Deferred Costs (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred leasing costs	$ 448,197	$ 447,002
Less: accumulated amortization	(277,945)	(269,834)
Deferred costs, net	$ 170,252	$ 177,168

Mortgages and Other Loans Pay_3

Mortgages and Other Loans Payable (Details)	1 Months Ended	3 Months Ended
	Jun. 30, 2020	Mar. 31, 2021USD ($)extension	Dec. 31, 2020USD ($)	Apr. 30, 2018USD ($)	Mar. 31, 2018USD ($)
Debt Instrument [Line Items]
Total fixed rate debt		$ 1,081,142,000	$ 1,083,683,000
Total floating rate debt		786,521,000	917,677,000
Total mortgages and other loans payable		1,867,663,000	2,001,360,000
Deferred financing costs, net of amortization		(18,962,000)	(21,388,000)
Total mortgages and other loans payable, net		1,848,701,000	1,979,972,000
Book value of collateral		2,400,000,000	2,500,000,000
Outstanding under line of credit facility		625,809,000	105,262,000
FHLB Facility, January 2021, 1
Debt Instrument [Line Items]
Total floating rate debt		0	10,000,000
FHLB Facility, January 2021, 2
Debt Instrument [Line Items]
Total floating rate debt		0	15,000,000
FHLB Facility January 2021
Debt Instrument [Line Items]
Total floating rate debt		0	35,000,000
2017 Master Repurchase Agreement
Debt Instrument [Line Items]
Total floating rate debt		0	0
Maximum facility capacity		400,000,000		$ 400,000,000	$ 300,000,000
Margin calls		$ 0
Extension option exercised, term	1 year	1 year
Outstanding under line of credit facility		$ 0
100 Church Street
Debt Instrument [Line Items]
Total fixed rate debt		$ 203,697,000	204,875,000
100 Church Street | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)		4.68%
420 Lexington Avenue
Debt Instrument [Line Items]
Total fixed rate debt		$ 292,672,000	294,035,000
420 Lexington Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)		3.99%
Landmark Square
Debt Instrument [Line Items]
Total fixed rate debt		$ 100,000,000	100,000,000
Landmark Square | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)		4.90%
485 Lexington Avenue
Debt Instrument [Line Items]
Total fixed rate debt		$ 450,000,000	450,000,000
485 Lexington Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)		4.25%
1080 Amsterdam Avenue
Debt Instrument [Line Items]
Total fixed rate debt		$ 34,773,000	34,773,000
Total fixed rate debt		33,900,000
Subordinate loan		$ 900,000
1080 Amsterdam Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)		3.59%
Term (in Years)		5 years
1080 Amsterdam Avenue | Mortgage loan | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)		3.50%
1080 Amsterdam Avenue | Subordinate loan | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)		7.00%
185 Broadway
Debt Instrument [Line Items]
Total floating rate debt		$ 168,870,000	158,478,000
185 Broadway | Weighted Average
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)		2.85%
609 Fifth Avenue
Debt Instrument [Line Items]
Total floating rate debt		$ 57,651,000	57,651,000
609 Fifth Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)		2.95%
220 East 42nd Street
Debt Instrument [Line Items]
Total floating rate debt		$ 510,000,000	510,000,000
220 East 42nd Street | Weighted Average
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)		2.75%
719 Seventh Avenue
Debt Instrument [Line Items]
Total floating rate debt		$ 50,000,000	50,000,000
719 Seventh Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)		1.20%
133 Greene Street
Debt Instrument [Line Items]
Total floating rate debt		$ 0	15,523,000
106 Spring Street
Debt Instrument [Line Items]
Total floating rate debt		0	38,025,000
712 Madison Avenue
Debt Instrument [Line Items]
Total floating rate debt		$ 0	$ 28,000,000
Construction Loans | 185 Broadway
Debt Instrument [Line Items]
Term (in Years)		3 years
Maximum facility capacity		$ 225,000,000
Number of extension options | extension		2
Period of extension options		1 year

Corporate Indebtedness - Additi

Corporate Indebtedness - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021USD ($)extension	Dec. 31, 2020USD ($)
Corporate Indebtedness
Outstanding under line of credit facility	$ 625,809,000	$ 105,262,000
Term Loan B, Maturity November 21, 2024 | Term loan
Corporate Indebtedness
Credit facility, maximum borrowing capacity	$ 200,000,000
Term Loan B, Maturity November 21, 2024 | LIBOR | Term loan
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.00%
Term Loan B, Maturity November 21, 2024 | LIBOR | Minimum | Term loan
Corporate Indebtedness
Interest rate added to base rate (as a percent)	0.85%
Term Loan B, Maturity November 21, 2024 | LIBOR | Maximum | Term loan
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.65%
Revolving credit facility
Corporate Indebtedness
Facility fee (as a percent)	0.20%
Outstanding under line of credit facility	$ 630,000,000
Revolving credit facility | Minimum
Corporate Indebtedness
Facility fee (as a percent)	0.125%
Revolving credit facility | Maximum
Corporate Indebtedness
Facility fee (as a percent)	0.30%
Term loan
Corporate Indebtedness
Long-term debt, carrying value	$ 1,500,000,000
Term loan | Line of Credit
Corporate Indebtedness
Long-term debt, carrying value	1,500,000,000	1,500,000,000
2012 Credit Facility
Corporate Indebtedness
Letters of credit	16,500,000
Ability to borrow under line of credit facility	900,000,000
2012 Credit Facility | Line of Credit
Corporate Indebtedness
Long-term debt, carrying value	625,800,000	$ 105,300,000
Term Loan A, Maturity March 31, 2023 | Term loan
Corporate Indebtedness
Credit facility, maximum borrowing capacity	$ 1,300,000,000
Term Loan A, Maturity March 31, 2023 | LIBOR | Term loan
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.10%
Term Loan A, Maturity March 31, 2023 | LIBOR | Minimum | Term loan
Corporate Indebtedness
Interest rate added to base rate (as a percent)	0.90%
Term Loan A, Maturity March 31, 2023 | LIBOR | Maximum | Term loan
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.75%
Revolving credit facility | Revolving Credit Facility, Maturity March 31, 2022 | Line of Credit
Corporate Indebtedness
Credit facility, maximum borrowing capacity	$ 1,500,000,000
Number of extensions | extension	2
Term of extension	6 months
Maximum borrowing capacity, optional expansion	$ 4,500,000,000
Revolving credit facility | Revolving Credit Facility, Maturity March 31, 2022 | LIBOR | Line of Credit
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.00%
Revolving credit facility | Revolving Credit Facility, Maturity March 31, 2022 | LIBOR | Minimum | Line of Credit
Corporate Indebtedness
Interest rate added to base rate (as a percent)	0.825%
Revolving credit facility | Revolving Credit Facility, Maturity March 31, 2022 | LIBOR | Maximum | Line of Credit
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.55%

Corporate Indebtedness - Senior

Corporate Indebtedness - Senior Unsecured Notes (Details) - USD ($)	1 Months Ended	3 Months Ended
	Oct. 31, 2017	Mar. 31, 2021	Dec. 31, 2020	Apr. 30, 2020
Debt disclosures by scheduled maturity date
Accreted Balance		$ 1,495,620,000	$ 1,495,275,000
Senior unsecured notes
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		1,250,000,000
Accreted Balance		1,251,647,000	1,251,889,000
Deferred financing costs, net		(3,025,000)	(3,670,000)
Accreted Balance, net of deferred financing costs		1,248,622,000	1,248,219,000
Senior unsecured notes | Senior Unsecured Notes Due August 2021
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		350,000,000
Accreted Balance		$ 350,000,000	350,000,000
Coupon Rate (as a percent)		1.52%
Initial Term (in Years)		3 years
Redemption price, percentage		100.00%
Senior unsecured notes | 3.25 Percent Senior Unsecured Notes Due October 2022
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		$ 500,000,000
Accreted Balance		$ 499,830,000	499,803,000
Coupon Rate (as a percent)		3.25%
Initial Term (in Years)		5 years
Senior unsecured notes | 4.50% Senior unsecured notes maturing on December 1, 2022
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		$ 300,000,000
Accreted Balance		$ 301,817,000	302,086,000
Coupon Rate (as a percent)	4.50%	4.50%
Initial Term (in Years)		10 years
Face amount of loan	$ 100,000,000
Redemption price, percentage	105.334%
Senior unsecured notes | 4.27% Senior unsecured notes maturing on December 17, 2025
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		$ 100,000,000
Accreted Balance		$ 100,000,000	$ 100,000,000
Coupon Rate (as a percent)		4.27%
Initial Term (in Years)		10 years
Interest Rate Swap | Senior Unsecured Notes Due August 2021
Debt disclosures by scheduled maturity date
Notional amount				$ 350,000,000
Derivative, fixed interest rate				0.54375%

Corporate Indebtedness - Junior

Corporate Indebtedness - Junior Subordinated Deferrable Interest Debentures and Principal Maturities (Details)	1 Months Ended	3 Months Ended
	Jun. 30, 2005USD ($)	Mar. 31, 2021USD ($)quarter
Principal Repayments and Joint Venture Debt
Remaining 2021		$ 526,901,000
2022		1,064,200,000
2023		2,496,594,000
2024		478,029,000
2025		100,823,000
Thereafter		681,116,000
Total principal repayments		$ 5,347,663,000
Trust Preferred Securities
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 100,000,000
LIBOR | Trust Preferred Securities
Debt Instrument [Line Items]
Interest rate added to base rate (as a percent)		1.25%
Interest payment deferment, number of consecutive quarters | quarter		8
Joint venture
Principal Repayments and Joint Venture Debt
Remaining 2021		$ 1,126,896,000
2022		227,701,000
2023		491,066,000
2024		620,843,000
2025		1,403,266,000
Thereafter		552,813,000
Total principal repayments		4,422,585,000
Joint venture | Trust Preferred Securities
Principal Repayments and Joint Venture Debt
Remaining 2021		0
2022		0
2023		0
2024		0
2025		0
Thereafter		100,000,000
Total principal repayments		100,000,000
Joint venture | Mortgages and other loans payable
Scheduled Amortization
Remaining 2021		8,031,000
2022		8,765,000
2023		6,594,000
2024		5,280,000
2025		823,000
Thereafter		924,000
Total amortization of debt		30,417,000
Principal Repayments and Joint Venture Debt
Remaining 2021		168,870,000
2022		255,435,000
2023		560,000,000
2024		272,749,000
2025		0
Thereafter		580,192,000
Total principal repayments		1,837,246,000
Joint venture | Revolving Credit Facility
Principal Repayments and Joint Venture Debt
Remaining 2021		0
2022		0
2023		630,000,000
2024		0
2025		0
Thereafter		0
Total principal repayments		630,000,000
Joint venture | Unsecured Term Loans
Principal Repayments and Joint Venture Debt
Remaining 2021		0
2022		0
2023		1,300,000,000
2024		200,000,000
2025		0
Thereafter		0
Total principal repayments		1,500,000,000
Joint venture | Senior Unsecured Notes
Principal Repayments and Joint Venture Debt
Remaining 2021		350,000,000
2022		800,000,000
2023		0
2024		0
2025		100,000,000
Thereafter		0
Total principal repayments		$ 1,250,000,000

Corporate Indebtedness - Schedu

Corporate Indebtedness - Schedule of Consolidated Interest Expense, Excluding Capitalized Interest (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest expense
Interest expense before capitalized interest	$ 39,868	$ 56,813
Interest on financing leases	1,492	1,663
Interest capitalized	(17,583)	(20,483)
Interest income	(389)	(499)
Interest expense, net	$ 23,388	$ 37,494

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Dec. 31, 2016	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Related Party Transactions
Operating lease rent		$ 6,739	$ 7,367
Amounts due from/to related parties
Due from joint ventures		26,500		$ 27,006
Other		7,810		7,651
Related party receivables		34,310		$ 34,657
Alliance Building Services
Related Party Transactions
Profit participation from related party		300	900
Payments made for services		2,300	3,900
Entity with Stephen L Green ownership interest
Related Party Transactions
Property management fees from related party		100	$ 200
One Vanderbilt
Related Party Transactions
Operating lease rent		100
One Vanderbilt | Marc Holliday
Related Party Transactions
Due from related party		1,400
One Vanderbilt | Andrew Mathias
Related Party Transactions
Due from related party		$ 1,000
One Vanderbilt | Minimum | Marc Holliday
Related Party Transactions
Percentage of profits due to investors (as a percentage)	1.50%
One Vanderbilt | Minimum | Andrew Mathias
Related Party Transactions
Percentage of profits due to investors (as a percentage)	1.00%
One Vanderbilt | Maximum | Marc Holliday
Related Party Transactions
Percentage of profits due to investors (as a percentage)	1.80%
One Vanderbilt | Maximum | Andrew Mathias
Related Party Transactions
Percentage of profits due to investors (as a percentage)	1.20%

Noncontrolling Interests on t_3

Noncontrolling Interests on the Company's Consolidated Financial Statements - Additional Information (Details) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)shares$ / shares	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)shares
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Redemption and conversion of common units | $		$ (1,536)
Net (loss) income | $	$ (476)	6,202
Accumulated other comprehensive income (loss) allocation | $	2,655	(2,886)
Partnership Interest
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Balance at beginning of period | $	358,262	409,862	$ 409,862
Distributions | $	(4,148)		(12,652)
Issuance of common units | $	4,483		12,018
Redemption and conversion of common units | $	(13,261)		(36,085)
Net (loss) income | $	(476)		20,016
Accumulated other comprehensive income (loss) allocation | $	2,655		(2,299)
Fair value adjustment | $	26,609		(32,598)
Balance at end of period | $	$ 374,124		$ 358,262
SL Green Operating Partnership
Organization
Number of units of operating partnership owned by the noncontrolling interest unit holders (shares)	4,156,282		3,938,823
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares)	4,156,282
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Redemption and conversion of common units | $		(1,536)
Accumulated other comprehensive income (loss) allocation | $	$ 2,655	$ (2,886)
SL Green Operating Partnership | 3.50% Series A
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	3.50%
Preferred units, shares authorized (in shares)	109,161
Number of preferred units issued (in shares)	109,161
Number of Units Outstanding (in shares)	109,161
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 35
Liquidation preference of preferred units (in dollars per share) | $ / shares	1,000
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 0
Number of company common stock issued on conversion of Series B preferred units	6.71348
SL Green Operating Partnership | Series F
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	700.00%
Preferred units, shares authorized (in shares)	60
Number of preferred units issued (in shares)	60
Number of Units Outstanding (in shares)	60
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 70
Liquidation preference of preferred units (in dollars per share) | $ / shares	1,000
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 29.12
SL Green Operating Partnership | 4.50% Series G
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	450.00%
Preferred units, shares authorized (in shares)	1,902,000
Number of preferred units issued (in shares)	1,902,000
Number of Units Outstanding (in shares)	718,697
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 1.1250
Liquidation preference of preferred units (in dollars per share) | $ / shares	25
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 88.50
Number of company common stock issue on redemption of operation partnership common units	1
SL Green Operating Partnership | Series K
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	350.00%
Preferred units, shares authorized (in shares)	700,000
Number of preferred units issued (in shares)	563,954
Number of Units Outstanding (in shares)	341,677
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 0.8750
Liquidation preference of preferred units (in dollars per share) | $ / shares	25
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 134.67
SL Green Operating Partnership | Series L
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	400.00%
Preferred units, shares authorized (in shares)	500,000
Number of preferred units issued (in shares)	378,634
Number of Units Outstanding (in shares)	372,634
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 1
Liquidation preference of preferred units (in dollars per share) | $ / shares	25
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 0
SL Green Operating Partnership | Series M
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	375.00%
Preferred units, shares authorized (in shares)	1,600,000
Number of preferred units issued (in shares)	1,600,000
Number of Units Outstanding (in shares)	96,357
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 0.9375
Liquidation preference of preferred units (in dollars per share) | $ / shares	25
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 0
SL Green Operating Partnership | Series P
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	400.00%
Preferred units, shares authorized (in shares)	200,000
Number of preferred units issued (in shares)	200,000
Number of Units Outstanding (in shares)	200,000
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 1
Liquidation preference of preferred units (in dollars per share) | $ / shares	25
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 0
SL Green Operating Partnership | Series Q
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	350.00%
Preferred units, shares authorized (in shares)	268,000
Number of preferred units issued (in shares)	268,000
Number of Units Outstanding (in shares)	268,000
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 0.8750
Liquidation preference of preferred units (in dollars per share) | $ / shares	25
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 148.95
SL Green Operating Partnership | Series R
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	350.00%
Preferred units, shares authorized (in shares)	400,000
Number of preferred units issued (in shares)	400,000
Number of Units Outstanding (in shares)	400,000
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 0.8750
Liquidation preference of preferred units (in dollars per share) | $ / shares	25
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 154.89
SL Green Operating Partnership | Series S
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	400.00%
Preferred units, shares authorized (in shares)	1,077,280
Number of preferred units issued (in shares)	1,077,280
Number of Units Outstanding (in shares)	1,077,280
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 1
Liquidation preference of preferred units (in dollars per share) | $ / shares	25
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 0
SL Green Operating Partnership | Series V
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)	350.00%
Preferred units, shares authorized (in shares)	40,000
Number of preferred units issued (in shares)	40,000
Number of Units Outstanding (in shares)	40,000
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 0.8750
Liquidation preference of preferred units (in dollars per share) | $ / shares	25
Operating partnership common stock value use for conversion of preferred units (in dollars per share) | $ / shares	$ 0
SL Green Operating Partnership | Series W
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Preferred units, shares authorized (in shares)	1
Number of preferred units issued (in shares)	1
Number of Units Outstanding (in shares)	1
Preferred stock, dividend, multiplier per common unit distribution	1,350
Operating Partnership | SL Green Operating Partnership
Organization
Noncontrolling interest in the operating partnership (as a percent)	5.65%		5.44%

Noncontrolling Interests on t_4

Noncontrolling Interests on the Company's Consolidated Financial Statements - Common Unit Activity (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Rollforward Analysis of Preferred Unit Activity
Redemption of preferred units		$ (1,536)
SL Green Operating Partnership
Rollforward Analysis of Preferred Unit Activity
Redemption of preferred units		(1,536)
SL Green Operating Partnership | Preferred Units
Rollforward Analysis of Preferred Unit Activity
Balance at beginning of period	$ 202,169	$ 283,285	$ 283,285
Issuance of preferred units	0		0
Redemption of preferred units	(3,631)		(82,750)
Dividends paid on preferred units	(1,731)		(6,163)
Accrued dividends on preferred units	1,696		7,797
Balance at end of period	$ 198,503		$ 202,169

Stockholders' Equity of the C_3

Stockholders' Equity of the Company - Additional Information (Details)	Jan. 15, 2021$ / shares	Jan. 08, 2021	Mar. 31, 2021USD ($)increase$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Jan. 07, 2021$ / shares	Mar. 31, 2020shares	Jun. 30, 2018USD ($)	Aug. 31, 2016USD ($)
Equity, Class of Treasury Stock [Line Items]
Authorized capital stock (shares) | shares			260,000,000
Authorized shares, par value (in dollars per share) | $ / shares			$ 0.01
Common stock, shares authorized (in shares) | shares			160,000,000	160,000,000
Common stock, par value (in dollars per share) | $ / shares			$ 0.01	$ 0.01
Excess stock, shares authorized (shares) | shares			75,000,000
Excess stock, par value (in dollars per share) | $ / shares			$ 0.01
Preferred stock, shares authorized (shares) | shares			25,000,000
Preferred stock, par value (in dollars per share) | $ / shares			$ 0.01
Excess shares issued (shares) | shares			0
Share repurchased (in shares) | shares			1,306,460	8,529,279	4,465,857	9,468,617	8,105,881
Average price paid per share (in dollars per share) | $ / shares			$ 61.46	$ 62.39	$ 86.06	$ 99.03	$ 104.61
2016 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount | $				$ 500,000,000	$ 500,000,000	$ 500,000,000	$ 500,000,000			$ 500,000,000	$ 1,000,000,000
Number of increases to share repurchase program | increase			5
Share repurchased (in shares) | shares			31,876,094	30,569,634	22,040,355	17,574,498	8,105,881
Stock repurchase program, authorized amount | $			$ 3,500,000,000
Common Stock
Equity, Class of Treasury Stock [Line Items]
Shares, outstanding (in shares) | shares			69,354,000	68,508,000	76,956,000				74,365,000
Share price (in dollars per share) | $ / shares								$ 58.15
Reverse stock split conversion ratio		1.02918
Common Stock | Cash Dividend
Equity, Class of Treasury Stock [Line Items]
Common stock, dividends, per share, cash paid (in dollars per share) | $ / shares	$ 0.3735
Common stock, dividends, per share, stock paid (in dollars per share) | $ / shares	0.0279
Common Stock | Stock Dividend
Equity, Class of Treasury Stock [Line Items]
Common stock, dividends, per share, stock paid (in dollars per share) | $ / shares	$ 0.0343
SL Green Operating Partnership | Common Stock
Equity, Class of Treasury Stock [Line Items]
Shares, outstanding (in shares) | shares			69,353,606

Stockholders' Equity of the C_4

Stockholders' Equity of the Company - Perpetual Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	Aug. 31, 2012	Mar. 31, 2021	Dec. 31, 2020	Feb. 28, 2018
Stockholders' Equity
Common stock, shares authorized (in shares)		160,000,000	160,000,000
Series I Preferred Stock
Stockholders' Equity
Preferred stock, shares outstanding (in shares)		9,200,000	9,200,000
Dividend rate preferred units (as a percent)		6.50%
Perpetual preferred stock, liquidation preference (in dollars per share)		$ 25	$ 25
Perpetual preferred stock, annual dividends per share (in dollars per share)		$ 1.625
Contributions of net proceeds from sale of preferred stock	$ 221.9
Dividend Reinvestment and Stock Purchase Plan (DRIP)
Stockholders' Equity
Common stock, shares authorized (in shares)				3,500,000

Stockholders' Equity of the C_5

Stockholders' Equity of the Company - Schedule of Common Stock Issued and Proceeds Received Dividend Reinvestments (Details) - Dividend Reinvestment and Stock Purchase Plan (DRIP) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Stockholders' Equity
Issuance of common stock (in shares)	5,483	1,727
Dividend reinvestments/stock purchases under the DRSPP	$ 351	$ 166

Stockholders' Equity of the C_6

Stockholders' Equity of the Company - Earnings per Share (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic Earnings:
Income attributable to SL Green common stockholders	$ (7,464)	$ 114,801
Less: distributed earnings allocated to participating securities	(371)	(113)
Less: undistributed earnings allocated to participating securities	0	(464)
Net Income attributable to common unitholders (numerator for basic earnings per unit)	(7,835)	114,224
Effect of Dilutive Securities:
Add back: dilutive effect of earnings allocated to participating securities	371	113
Add back: undistributed earnings allocated to participating securities	0	464
Redemption of units to common shares	(476)	6,202
Diluted Earnings:
Income attributable to SL Green common stockholders	$ (7,940)	$ 121,003
Basic Shares:
Weighted average common shares outstanding (shares)	69,010,000	75,656,000
Effect of Dilutive Securities:
Operating Partnership units redeemable for common shares (shares)	4,148,000	4,220,000
Stock-based compensation plans (shares)	595,000	476,000
Contingently issuable shares from special dividend declared December 4, 2020 (in shares)	317,000	0
Diluted weighted average common stock outstanding (shares)	74,070,000	80,352,000
Common stock shares excluded from the diluted shares outstanding (shares)	1,159,343

Partners' Capital of the Oper_3

Partners' Capital of the Operating Partnership - Additional Information (Details) - shares	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Common Stock
Stockholders' Equity
Units outstanding (units)	69,354,000	68,508,000	74,365,000	76,956,000
SL Green Operating Partnership
Stockholders' Equity
Number of units of operating partnership owned by the noncontrolling interest unit holders (units)	4,156,282	3,938,823
SL Green Operating Partnership | Series I Preferred Units
Stockholders' Equity
Units outstanding (units)	9,200,000
Period of restriction to redeem OP Units	1 year
Conversion of stock, shares issued	1
SL Green Operating Partnership | Common Stock
Stockholders' Equity
Units outstanding (units)	69,353,606

Partners' Capital of the Oper_4

Partners' Capital of the Operating Partnership - EPS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator
Less: distributed earnings allocated to participating securities	$ (371)	$ (113)
Less: undistributed earnings allocated to participating securities	0	(464)
Net Income attributable to common unitholders (numerator for basic earnings per unit)	(7,835)	114,224
Add back: dilutive effect of earnings allocated to participating securities	(371)	(113)
Add back: undistributed earnings allocated to participating securities	0	(464)
Income attributable to SL Green common stockholders	$ (7,940)	121,003
Denominator
Common stock shares excluded from the diluted shares outstanding (shares)	1,159,343
SL Green Operating Partnership
Numerator
Net income attributable to SLGOP common unitholders	$ (7,940)	121,003
Less: distributed earnings allocated to participating securities	(371)	(113)
Less: undistributed earnings allocated to participating securities	0	(464)
Net Income attributable to common unitholders (numerator for basic earnings per unit)	(8,311)	120,426
Add back: dilutive effect of earnings allocated to participating securities	371	113
Add back: undistributed earnings allocated to participating securities	0	464
Income attributable to SL Green common stockholders	$ (7,940)	$ 121,003
Denominator
Basic weighted average common units outstanding (in shares)	73,158,000	79,876,000
Stock-based compensation plans (shares)	595,000	476,000
Contingently issuable units from special distribution declared December 4, 2020 (in shares)	317,000	0
Diluted weighted average common units outstanding (shares)	74,070,000	80,352,000
Common stock shares excluded from the diluted shares outstanding (shares)	1,159,343	1,170,579

Share-based Compensation - Addi

Share-based Compensation - Additional Information (Details) fungibleUnit in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)unit / sharesfungibleUnitunitshares	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)shares	Dec. 31, 2019shares	Jan. 01, 2008shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized to assets associated with compensation expense related to our long-term compensation plans, restricted stock and stock options	$ 500,000	$ 600,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of commencement of option vesting, from date of grant (in years)	1 year
Options granted (in shares) | shares	0		0
Remaining weighted average contractual life of the options outstanding (in years)	1 year 10 months 24 days
Remaining average contractual life of the options exercisable (in years)	1 year 10 months 24 days
Stock options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period (in years)	5 years
Options vesting period (in years)	1 year
Stock options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period (in years)	10 years
Options vesting period (in years)	5 years
Class O LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred unit distributions as a percentage of common unit distributions	10.00%
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 2,067,125		$ 10,895,459
Total unrecognized compensation cost related to unvested stock awards	$ 14,000,000
Weighted average period for recognition of compensation cost related to unvested stock awards (in years)	2 years
Annual award vesting rate, low end of range (as a percent)	15.00%
Annual award vesting rate, high end of range (as a percent)	35.00%
Fair value of restricted stock vested during the period	$ 10,900,000		12,500,000
Weighted average fair value of options granted during the period	$ 9,214,531		$ 734,315
Awards granted (in shares) | shares	145,845		8,959
Awards outstanding (in shares) | shares	3,573,082		3,439,674	3,465,347
LTIP units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of options granted during the period	$ 40,300,000		$ 37,000,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	9,100,000	3,000,000
Total unrecognized compensation cost related to unvested stock awards	$ 65,900,000
Weighted average period for recognition of compensation cost related to unvested stock awards (in years)	2 years
All other awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	10 years
Third Amendment and Restated 2005 Stock Option and Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum fungible units that may be granted (in shares) | unit	27,030,000
Fungible units per share (in fungible units per share) | unit / shares	3.74
Shares that may be issued if equal to fungible units (shares) (less than) | shares	27,030,000
Fungible units | fungibleUnit	1.9
Third Amendment and Restated 2005 Stock Option and Incentive Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 0	20,000
Total unrecognized compensation cost related to unvested stock awards	$ 0
Stock options, stock appreciation rights and other awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fungible units per share (in fungible units per share) | unit / shares	0.73
Award expiration period (in years)	5 years
All other awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fungible units per share (in fungible units per share) | unit / shares	1
Deferred Stock Compensation Plan for Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 1,800,000	$ 1,800,000
Maximum percentage of the annual retainer fee, chairman fees and meeting fees that may be deferred by non-employee directors (percent)	100.00%
Awards granted (in shares) | shares	18,290
Shares issued (in shares) | shares	12,064
Awards outstanding (in shares) | shares	159,066
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for issuance (shares) | shares					500,000
Duration of each offering period starting the first day of each calendar quarter (in months)	3 months
Discount from market price	85.00%
Shares of common stock issued (shares) | shares	157,576

Share-based Compensation - Stoc

Share-based Compensation - Stock Options and Restricted Stock Activity (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Stock options
Options Outstanding
Balance at beginning of period (in shares)	784,995	1,007,665
Granted (in shares)	0	0
Exercised (in shares)	0	0
Lapsed or cancelled (in shares)	(9,716)	(222,670)
Balance at end of period (in shares)	775,279	784,995
Options exercisable at end of period (in shares)	775,278	782,022
Weighted Average Exercise Price
Balance at beginning of year (in dollars per share)	$ 102.62	$ 105.35
Granted (in dollars per share)	0	0
Exercised (in dollars per share)	0	0
Lapsed or cancelled (in dollars per share)	86.13	114.97
Balance at end of period (in dollars per share)	102.83	102.62
Options exercisable at end of period (in dollars per share)	$ 102.83	$ 102.62
Restricted Stock Awards
Options Outstanding
Total fair value of options granted during the period	$ 9,214,531	$ 734,315
Summary of restricted stock
Balance at beginning of year (in shares)	3,439,674	3,465,347
Granted (in shares)	145,845	8,959
Cancelled (in shares)	(12,437)	(34,632)
Balance at end of period (in shares)	3,573,082	3,439,674
Vested during the period (in shares)	117,487	128,891

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	$ 4,935,795
Other comprehensive income before reclassifications	42,548
Amounts reclassified from accumulated other comprehensive loss	5,802
Ending Balance	4,935,620
Deferred net losses from terminated hedges	(600)	$ (500)
Net unrealized (loss) gain on derivative instruments
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	(57,415)
Other comprehensive income before reclassifications	9,771
Amounts reclassified from accumulated other comprehensive loss	4,196
Ending Balance	(43,448)
Net unrealized gain (loss) on marketable securities
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	1,021
Other comprehensive income before reclassifications	(247)
Amounts reclassified from accumulated other comprehensive loss	0
Ending Balance	774
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	(67,247)
Ending Balance	(18,897)
Joint venture
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	6,349,006
Ending Balance	5,838,595
Joint venture | Net unrealized (loss) gain on derivative instruments
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	(10,853)
Other comprehensive income before reclassifications	33,024
Amounts reclassified from accumulated other comprehensive loss	1,606
Ending Balance	$ 23,777

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value of Financial Instruments
Marketable securities	$ 23,784	$ 28,570
Interest rate cap and swap agreements (included in Other assets)	365	28
Debt and preferred equity investments	1,097,202	1,076,542
Equity method investments	3,698,701	3,823,322
Additional amount of financing receivables included in other assets	66,400	66,200
Carrying Value
Fair Value of Financial Instruments
Debt and preferred equity investments	1,097,202	1,076,542
Fixed rate debt	3,932,789	3,135,572
Variable rate debt	1,416,521	1,827,677
Total	5,349,310	4,963,249
Fair Value
Fair Value of Financial Instruments
Marketable securities	23,784	28,570
Total	5,448,603	5,059,815
Estimated fair value of debt and preferred equity investments, low end of range	1,000,000	1,000,000
Estimated fair value of debt and preferred equity investments, high end of range	1,100,000	1,100,000
Level 1
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in Other assets)	0	0
Level 2
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in Other assets)	365	28
Level 3
Fair Value of Financial Instruments
Marketable securities	0	0
Interest rate cap and swap agreements (included in Other assets)	0	0
Level 3 | Fair Value
Fair Value of Financial Instruments
Fixed rate debt	4,027,789	3,237,075
Variable rate debt	1,420,814	1,822,740
Equity marketable securities | Level 1
Fair Value of Financial Instruments
Marketable securities	0	0
Commercial mortgage-backed securities
Fair Value of Financial Instruments
Marketable securities	23,784	28,570
Commercial mortgage-backed securities | Level 2
Fair Value of Financial Instruments
Marketable securities	23,784	28,570
Joint venture
Fair Value of Financial Instruments
Equity method investments	3,698,701
Accrued Interest Payable And Other
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in Other liabilities)	47,033	61,217
Accrued Interest Payable And Other | Level 1
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in Other liabilities)	0	0
Accrued Interest Payable And Other | Level 2
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in Other liabilities)	47,033	61,217
Accrued Interest Payable And Other | Level 3
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in Other liabilities)	$ 0	$ 0

Financial Instruments_ Deriva_3

Financial Instruments: Derivatives and Hedging (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Financial Instruments: Derivatives and Hedging
Fair Value	$ 365,000		$ 28,000
Gain (loss) from changes in fair value	0	$ 0
Fair value of derivatives in a net liability position	48,300,000
Aggregate termination value	49,000,000
Estimated current balance held in accumulated other comprehensive loss to be reclassified into earnings within the next 12 months	16,600,000
Share of joint venture of accumulated other comprehensive loss reclassified into equity in net income from unconsolidated joint ventures within the next 12 months	2,200,000
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	45,175,000	(52,171,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income	(6,088,000)	(1,436,000)
Interest Rate Swap Expiring August 2021
Financial Instruments: Derivatives and Hedging
Notional Value	$ 350,000,000
Strike Rate	0.544%
Fair Value	$ (472,000)
Interest Rate Cap Expiring November 2021
Financial Instruments: Derivatives and Hedging
Notional Value	$ 111,869,000
Strike Rate	3.50%
Fair Value	$ 0
Interest Rate Cap Expiring December 2021
Financial Instruments: Derivatives and Hedging
Notional Value	$ 510,000,000
Strike Rate	3.00%
Fair Value	$ 0
Interest Rate Swap Expiring February 2022
Financial Instruments: Derivatives and Hedging
Notional Value	$ 200,000,000
Strike Rate	0.138%
Fair Value	$ (3,000)
Interest Rate Swap Expiring February 2022, 2
Financial Instruments: Derivatives and Hedging
Notional Value	$ 100,000,000
Strike Rate	0.136%
Fair Value	$ 0
Interest Rate Cap Expiring March 2022
Financial Instruments: Derivatives and Hedging
Notional Value	$ 85,000,000
Strike Rate	4.00%
Fair Value	$ 0
Interest Rate Swap Expiring January 2023
Financial Instruments: Derivatives and Hedging
Notional Value	$ 100,000,000
Strike Rate	0.212%
Fair Value	$ 95,000
Interest Rate Swap Expiring February 2023
Financial Instruments: Derivatives and Hedging
Notional Value	$ 400,000,000
Strike Rate	0.16%
Fair Value	$ 270,000
Interest Rate Swap Expiring in July 2023
Financial Instruments: Derivatives and Hedging
Notional Value	$ 200,000,000
Strike Rate	1.131%
Fair Value	$ (4,017,000)
Interest Rate Swap Expiring in July 2023, 2
Financial Instruments: Derivatives and Hedging
Notional Value	$ 100,000,000
Strike Rate	1.161%
Fair Value	$ (2,077,000)
Interest Rate Swap Expiring January 2024
Financial Instruments: Derivatives and Hedging
Notional Value	$ 150,000,000
Strike Rate	2.696%
Fair Value	$ (9,675,000)
Interest Rate Swap Expiring January 2026
Financial Instruments: Derivatives and Hedging
Notional Value	$ 150,000,000
Strike Rate	2.721%
Fair Value	$ (13,117,000)
Interest Rate Swap Expiring January 2026, 2
Financial Instruments: Derivatives and Hedging
Notional Value	$ 200,000,000
Strike Rate	2.74%
Fair Value	$ (17,672,000)
Interest Rate Contract
Financial Instruments: Derivatives and Hedging
Fair Value	(46,668,000)
Interest Rate Swaps/Caps
Financial Instruments: Derivatives and Hedging
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	10,220,000	(45,082,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income	(4,388,000)	(725,000)
Joint venture
Financial Instruments: Derivatives and Hedging
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss)	34,955,000	(7,089,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income	(1,700,000)	$ (711,000)
Joint venture | Interest Rate Contract
Financial Instruments: Derivatives and Hedging
Fair Value	42,081,000
Joint venture | Interest Rate Swap Expiring February 2026
Financial Instruments: Derivatives and Hedging
Notional Value	$ 177,000,000
Strike Rate	1.669%
Fair Value	$ (6,459,000)
Joint venture | Interest Rate Cap Expiring September 2021
Financial Instruments: Derivatives and Hedging
Notional Value	$ 375,000,000
Strike Rate	2.60%
Fair Value	$ 0
Joint venture | Interest Rate Cap Expiring September 2021, 2
Financial Instruments: Derivatives and Hedging
Notional Value	$ 20,026,000
Strike Rate	2.60%
Fair Value	$ 0
Joint venture | Interest Rate Cap Expiring August 2022
Financial Instruments: Derivatives and Hedging
Notional Value	$ 198,000,000
Strike Rate	4.00%
Fair Value	$ 2,000
Joint venture | Interest Rate Cap Expiring February 2022
Financial Instruments: Derivatives and Hedging
Notional Value	$ 220,000,000
Strike Rate	4.00%
Fair Value	$ 0
Joint venture | Interest Rate Cap Expiring September 2023
Financial Instruments: Derivatives and Hedging
Notional Value	$ 550,000,000
Strike Rate	3.75%
Fair Value	$ 138,000
Joint venture | Interest Rate Cap Expiring September 2021, 3
Financial Instruments: Derivatives and Hedging
Notional Value	$ 1,075,000,000
Strike Rate	3.75%
Fair Value	$ 0
Joint venture | Interest Rate Cap Expiring September 2021, 4
Financial Instruments: Derivatives and Hedging
Notional Value	$ 125,000,000
Strike Rate	3.75%
Fair Value	$ 0
Joint venture | Interest Rate Cap Expiring October 2024
Financial Instruments: Derivatives and Hedging
Notional Value	$ 1,250,000,000
Strike Rate	1.25%
Fair Value	$ 5,764,000
Joint venture | Interest Rate Cap Expiring January 2023
Financial Instruments: Derivatives and Hedging
Notional Value	$ 23,000,000
Strike Rate	4.75%
Fair Value	$ 1,000
Joint venture | Interest Rate Swap Expiring June 2031
Financial Instruments: Derivatives and Hedging
Notional Value	$ 2,250,000,000
Strike Rate	1.611%
Fair Value	$ 42,635,000

Lease Income - Lease Income (De

Lease Income - Lease Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Fixed lease payments	$ 164,679	$ 194,224
Variable lease payments	25,279	27,168
Total lease payments	189,958	221,392
Amortization of acquired above and below-market leases	(1,869)	1,239
Total rental revenue	188,089	222,631
Sublease Income	65,800	66,300
Interest income	$ 1,101	$ 0

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating leases, minimum lease term	1 year
Operating lease, weighted average discount rate, percent	4.52%
Operating lease, weighted average remaining lease term	27 years
Financing leases
Remaining 2021	$ 31,136
2022	3,522
2023	3,570
2024	3,641
2025	3,810
2026	3,858
Thereafter	256,692
Total minimum lease payments	306,229
Amount representing interest	(153,607)
Lease liabilities	152,622	$ 152,521
Operating leases
Remaining 2021	31,954
2022	29,386
2023	29,502
2024	30,545
2025	30,772
2026	30,911
Thereafter	631,532
Total minimum lease payments	814,602
Amount discounted using incremental borrowing rate	(359,217)
Lease liabilities	$ 455,385	$ 339,458
711 Third Avenue
Lessee, Lease, Description [Line Items]
Ownership Interest Disposed	50.00%

Commitments and Contingencies -

Commitments and Contingencies - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Lease Costs
Operating lease costs before capitalized operating lease costs	$ 7,567	$ 8,113
Operating lease costs capitalized	(828)	(746)
Operating lease costs, net	6,739	7,367
Finance Lease, Costs [Abstract]
Interest on financing leases	1,492	1,663
Interest on financing leases capitalized	0	(747)
Interest on financing leases, net	1,492	916
Finance lease, right-of-use asset, amortization	180	305
Financing lease costs, net	$ 1,672	$ 1,221
Operating lease, weighted average discount rate, percent	4.52%
Operating lease, weighted average remaining lease term	27 years

Segment Information - Additiona

Segment Information - Additional Information (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2021USD ($)segment	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Segment information
Number of reportable segments | segment		2
Total revenues		$ 226,102	$ 314,303
Net (loss) income		(3,855)	127,114
Total assets	[1]	12,044,045		$ 11,707,567
Marketing, general and administrative		22,885	19,570
Operating Segments | Real Estate Segment
Segment information
Total revenues		206,829	275,770
Net (loss) income		(20,027)	111,233
Total assets		10,896,203		10,579,899
Operating Segments | Debt and Preferred Equity Segment
Segment information
Total revenues		19,273	38,533
Net (loss) income		16,172	$ 15,881
Total assets		$ 1,147,842		$ 1,127,668
[1]	The Company's consolidated balance sheets include assets and liabilities of consolidated variable interest entities ("VIEs"). See Note 2. The consolidated balance sheets include the following amounts related to our consolidated VIEs, excluding the Operating Partnership: $179.6 million and $41.2 million of land, $282.3 million and $57.9 million of building and improvements, $2.0 million and $2.0 million of building and leasehold improvements, $53.2 million and $37.8 million of right of use assets, $16.4 million and $10.3 million of accumulated depreciation, $297.1 million and $289.5 million of other assets included in other line items, $368.6 million and $94.0 million of real estate debt, net, $0.9 million and $0.7 million of accrued interest payable, $45.3 million and $29.9 million of lease liabilities, and $31.2 million and $56.6 million of other liabilities included in other line items as of March 31, 2021 and December 31, 2020, respectively.