SL Green Operating Partnership 10-Q 9 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Nov. 07, 2017
Document Information [Line Items]
Entity Registrant Name	SL GREEN REALTY CORP
Entity Central Index Key	1,040,971
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		98,265,715
SL Green Operating Partnership
Document Information [Line Items]
Entity Registrant Name	SL GREEN OPERATING PARTNERSHIP, LP.
Entity Central Index Key	1,492,869
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,497,224

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Commercial real estate properties, at cost:
Land and land interests		$ 2,917,993	$ 3,309,710
Building and improvements		7,468,436	7,948,852
Building leasehold and improvements		1,444,698	1,437,325
Properties under capital lease		47,445	47,445
Total commercial real estate properties, at cost		11,878,572	12,743,332
Less: accumulated depreciation		(2,457,071)	(2,264,694)
Total commercial real estate properties, net		9,421,501	10,478,638
Assets held for sale		127,663	0
Cash and cash equivalents		241,489	279,443
Restricted cash		107,763	90,524
Investments in marketable securities		28,802	85,110
Tenant and other receivables, net of allowance of $18,365 and $16,592 in 2017 and 2016, respectively		54,663	53,772
Related party receivables		24,068	15,856
Deferred rents receivable, net of allowance of $21,257 and $25,203 in 2017 and 2016, respectively		393,793	442,179
Debt and preferred equity investments, net of discounts and deferred origination fees of $24,782 and $16,705 in 2017 and 2016, respectively		2,020,739	1,640,412
Investments in unconsolidated joint ventures		2,045,796	1,890,186
Deferred costs, net		247,981	267,600
Other assets		395,612	614,067
Total assets	[1]	15,109,870	15,857,787
Liabilities
Mortgages and other loans payable, net		3,804,174	4,073,830
Revolving credit facility, net		275,832	0
Unsecured term loan, net		1,180,506	1,179,521
Unsecured notes, net		1,064,544	1,128,315
Accrued interest payable		34,367	36,052
Other liabilities		95,718	206,238
Accounts payable and accrued expenses		144,767	190,583
Deferred revenue		252,779	217,955
Capital lease obligations		42,660	42,132
Deferred land leases payable		3,075	2,583
Dividend and distributions payable		85,007	87,271
Security deposits		68,465	66,504
Liabilities related to assets held for sale		1,141	0
Junior subordinated deferrable interest debentures held by trusts that issued trust preferred securities		100,000	100,000
Total liabilities	[1]	7,153,035	7,330,984
Commitments and contingencies
Noncontrolling interests in Operating Partnership		470,898	473,882
Preferred units		301,885	302,010
Equity
Series I Preferred Stock, $0.01 par value, $25.00 liquidation preference, 9,200 issued and outstanding at both September 30, 2017 and December 31, 2016		221,932	221,932
Common stock, $0.01 par value, 160,000 shares authorized and 98,501 and 101,617 issued and outstanding at September 30, 2017 and December 31, 2016, respectively (including 1,055 shares held in treasury at September 30, 2017 and December 31, 2016)		985	1,017
Additional paid-in-capital		5,294,500	5,624,545
Treasury stock at cost		(124,049)	(124,049)
Accumulated other comprehensive income		14,185	22,137
Retained earnings		1,410,332	1,578,893
Total SL Green stockholders' equity		6,817,885	7,324,475
Noncontrolling interests in other partnerships		366,167	426,436
Total equity		7,184,052	7,750,911
SL Green stockholders equity:
Total liabilities and equity/capital		15,109,870	15,857,787
SL Green Operating Partnership
Commercial real estate properties, at cost:
Land and land interests		2,917,993	3,309,710
Building and improvements		7,468,436	7,948,852
Building leasehold and improvements		1,444,698	1,437,325
Properties under capital lease		47,445	47,445
Total commercial real estate properties, at cost		11,878,572	12,743,332
Less: accumulated depreciation		(2,457,071)	(2,264,694)
Total commercial real estate properties, net		9,421,501	10,478,638
Assets held for sale		127,663	0
Cash and cash equivalents		241,489	279,443
Restricted cash		107,763	90,524
Investments in marketable securities		28,802	85,110
Tenant and other receivables, net of allowance of $18,365 and $16,592 in 2017 and 2016, respectively		54,663	53,772
Related party receivables		24,068	15,856
Deferred rents receivable, net of allowance of $21,257 and $25,203 in 2017 and 2016, respectively		393,793	442,179
Debt and preferred equity investments, net of discounts and deferred origination fees of $24,782 and $16,705 in 2017 and 2016, respectively		2,020,739	1,640,412
Investments in unconsolidated joint ventures		2,045,796	1,890,186
Deferred costs, net		247,981	267,600
Other assets		395,612	614,067
Total assets	[2]	15,109,870	15,857,787
Liabilities
Mortgages and other loans payable, net		3,804,174	4,073,830
Revolving credit facility, net		275,832	0
Unsecured term loan, net		1,180,506	1,179,521
Unsecured notes, net		1,064,544	1,128,315
Accrued interest payable		34,367	36,052
Other liabilities		95,718	206,238
Accounts payable and accrued expenses		144,767	190,583
Deferred revenue		252,779	217,955
Capital lease obligations		42,660	42,132
Deferred land leases payable		3,075	2,583
Dividend and distributions payable		85,007	87,271
Security deposits		68,465	66,504
Liabilities related to assets held for sale		1,141	0
Junior subordinated deferrable interest debentures held by trusts that issued trust preferred securities		100,000	100,000
Total liabilities	[2]	7,153,035	7,330,984
Commitments and contingencies
Noncontrolling interests in Operating Partnership		470,898	473,882
Limited partner interests in SLGOP (4,542 and 4,364 limited partner common units outstanding at September 30, 2017 and December 31, 2016, respectively)		470,898	473,882
Preferred units		301,885	302,010
Equity
Accumulated other comprehensive income		14,185	22,137
SL Green stockholders equity:
Series I Preferred Units, $25.00 liquidation preference, 9,200 issued and outstanding at both September 30, 2017 and December 31, 2016		221,932	221,932
SL Green partners' capital (1,020 and 1,049 general partner common units and 96,426 and 99,513 limited partner common units outstanding at September 30, 2017 and December 31, 2016, respectively)		6,581,768	7,080,406
Total SLGOP partners' capital		6,817,885	7,324,475
Noncontrolling interests in other partnerships		366,167	426,436
Total capital		7,184,052	7,750,911
Total liabilities and equity/capital		$ 15,109,870	$ 15,857,787
[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: $384.3 million and $412.3 million of land, $1.4 billion and $1.5 billion of building and improvements, $2.0 million and $2.0 million of building and leasehold improvements, $47.4 million and $47.4 million of properties under capital lease, $323.3 million and $327.2 million of accumulated depreciation, $235.4 million and $244.2 million of other assets included in other line items, $627.8 million and $621.8 million of real estate debt, net, $2.5 million and $2.2 million of accrued interest payable, $42.7 million and $42.1 million of capital lease obligations, and $58.5 million and $73.3 million of other liabilities included in other line items as of September 30, 2017 and December 31, 2016, 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: $384.3 million and $412.3 million of land, $1.4 billion and $1.5 billion of building and improvements, $2.0 million and $2.0 million of building and leasehold improvements, $47.4 million and $47.4 million of properties under capital lease, $323.3 million and $327.2 million of accumulated depreciation, $235.4 million and $244.2 million of other assets included in other line items, $627.8 million and $621.8 million of real estate debt, net, $2.5 million and $2.2 million of accrued interest payable, $42.7 million and $42.1 million of capital lease obligations, and $58.5 million and $73.3 million of other liabilities included in other line items as of September 30, 2017 and December 31, 2016, respectively.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Tenant and other receivables, allowance	$ 18,365	$ 16,592
Deferred rents receivable, allowance	21,257	25,203
Debt and preferred equity investments, discount and deferred origination fees	$ 24,782	$ 16,705
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)	98,501,000	101,617,000
Common stock, shares outstanding (in shares)	98,501,000	101,617,000
Treasury stock, shares (in shares)	1,055,000	1,055,000
Land and land interests	$ 2,917,993	$ 3,309,710
Building and improvements	7,468,436	7,948,852
Building leasehold and improvements	1,444,698	1,437,325
Properties under capital lease	47,445	47,445
Accumulated depreciation	2,457,071	2,264,694
Other assets	395,612	614,067
Mortgages and other loans payable, net	3,804,174	4,073,830
Accrued interest payable	34,367	36,052
Capital lease obligations	42,660	42,132
Other liabilities	$ 95,718	$ 206,238
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
Consolidated VIEs
Land and land interests	$ 384,300	$ 412,300
Building and improvements	1,400,000	1,500,000
Building leasehold and improvements	2,000	2,000
Properties under capital lease	47,400	47,400
Accumulated depreciation	323,300	327,200
Other assets	235,400	244,200
Mortgages and other loans payable, net	627,800	621,800
Accrued interest payable	2,500	2,200
Capital lease obligations	42,700	42,100
Other liabilities	58,500	73,300
SL Green Operating Partnership
Tenant and other receivables, allowance	18,365	16,592
Deferred rents receivable, allowance	21,257	25,203
Debt and preferred equity investments, discount and deferred origination fees	$ 24,782	$ 16,705
Limited partner interests in Operating Partnership, limited partner common units outstanding (shares)	4,542,000	4,364,000
SL Green partner's capital, general partner common units outstanding (shares)	1,020,000	1,049,000
SL Green partners' capital, limited partner common units outstanding (shares)	96,426,000	99,513,000
Land and land interests	$ 2,917,993	$ 3,309,710
Building and improvements	7,468,436	7,948,852
Building leasehold and improvements	1,444,698	1,437,325
Properties under capital lease	47,445	47,445
Accumulated depreciation	2,457,071	2,264,694
Other assets	395,612	614,067
Mortgages and other loans payable, net	3,804,174	4,073,830
Accrued interest payable	34,367	36,052
Capital lease obligations	42,660	42,132
Other liabilities	$ 95,718	$ 206,238
SL Green Operating Partnership | Series I Preferred Stock
Preferred units, liquidation preference (in dollars per share)	$ 25	$ 25
Preferred units, shares issued	9,200,000	9,200,000
Preferred units, shares outstanding	9,200,000	9,200,000
SL Green Operating Partnership | Consolidated VIEs
Land and land interests	$ 384,300	$ 412,300
Building and improvements	1,400,000	1,500,000
Building leasehold and improvements	2,000	2,000
Properties under capital lease	47,400	47,400
Accumulated depreciation	323,300	327,200
Other assets	235,400	244,200
Mortgages and other loans payable, net	267,800	621,800
Accrued interest payable	2,500	2,200
Capital lease obligations	42,700	42,100
Other liabilities	$ 58,500	$ 73,300

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues
Rental revenue, net	$ 274,765	$ 281,482	$ 835,501	$ 1,043,898
Escalation and reimbursement	44,749	53,130	131,561	147,357
Investment income	47,820	75,396	148,741	174,347
Other income	7,266	6,673	34,328	124,137
Total revenues	374,600	416,681	1,150,131	1,489,739
Expenses
Operating expenses, including related party expenses of $5,505 and $14,941 in 2017 and $5,042 and $15,171 in 2016.	75,927	79,425	221,285	234,269
Real estate taxes	64,160	64,133	186,173	187,931
Ground rent	8,307	8,338	24,923	24,953
Interest expense, net of interest income	65,634	72,565	196,112	256,326
Amortization of deferred financing costs	4,008	4,815	12,201	20,180
Depreciation and amortization	91,728	112,665	318,916	717,015
Transaction related costs	186	2,593	365	5,987
Marketing, general and administrative	23,963	25,458	72,362	73,974
Total expenses	333,913	369,992	1,032,337	1,520,635
Income (loss) before equity in net income (loss) from unconsolidated joint ventures, equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain (loss) on sale of real estate, net, depreciable real estate reserves, and gain (loss) on sale of investment in marketable securities	40,687	46,689	117,794	(30,896)
Equity in net income (loss) from unconsolidated joint ventures	4,078	(3,968)	14,104	11,969
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	1,030	225	16,166	43,588
Gain (loss) on sale of real estate, net	0	397	(3,256)	210,750
Depreciable real estate reserves	0	0	(85,336)	(10,387)
Gain (loss) on sale of investment in marketable securities	0	0	3,262	(83)
Net income	45,795	43,343	62,734	224,941
Net (income) loss attributable to noncontrolling interests:
Noncontrolling interests in the Operating Partnership	(1,812)	(1,663)	(2,707)	(8,171)
Noncontrolling interests in other partnerships	1,474	(836)	18,179	(6,245)
Preferred units distributions	(2,850)	(2,854)	(8,551)	(8,382)
Net income (loss) attributable to SL Green/SLGOP	42,607	37,990	69,655	202,143
Perpetual preferred stock dividends	(3,738)	(3,738)	(11,213)	(11,213)
Amounts attributable to SL Green common stockholders:
Income (loss) before depreciable real estate reserves and gains (losses) on sale	37,885	33,657	127,685	(43,041)
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	984	215	15,456	41,805
Gain (loss) on sale of real estate, net	0	380	(3,113)	202,128
Depreciable real estate reserves	0	0	(81,586)	(9,962)
Net income attributable to SL Green common stockholders	$ 38,869	$ 34,252	$ 58,442	$ 190,930
Basic earnings per share:
Income (loss) before depreciable real estate reserves and gains (losses) on sale (in dollars per share)	$ 0.39	$ 0.34	$ 1.28	$ (0.43)
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (in dollars per share)	0.01	0	0.16	0.42
Gain (loss) on sale of real estate, net	0	0	(0.03)	2.02
Depreciable real estate reserves	0	0	(0.82)	(0.10)
Net income attributable to SL Green common stockholders (usd per share)	0.40	0.34	0.59	1.91
Diluted earnings per share:
Income (loss) before depreciable real estate reserves and gains (losses) on sale (in dollars per share)	0.39	0.34	1.28	(0.43)
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (in dollars per share)	0.01	0	0.16	0.42
Gain on sale of real estate (in dollars per share)	0	0	(0.03)	2.01
Depreciable real estate reserves (in dollars per share)	0	0	(0.82)	(0.10)
Net income attributable to SL Green common stockholders (usd per share)	0.40	0.34	0.59	1.90
Dividends per share/unit (usd per share)	$ 0.775	$ 0.72	$ 2.325	$ 2.16
Basic weighted average common shares outstanding (in shares)	97,783	100,233	99,431	100,140
Diluted weighted average common shares and common share equivalents outstanding (in shares)	102,570	105,143	104,280	104,761
SL Green Operating Partnership
Revenues
Rental revenue, net	$ 274,765	$ 281,482	$ 835,501	$ 1,043,898
Escalation and reimbursement	44,749	53,130	131,561	147,357
Investment income	47,820	75,396	148,741	174,347
Other income	7,266	6,673	34,328	124,137
Total revenues	374,600	416,681	1,150,131	1,489,739
Expenses
Operating expenses, including related party expenses of $5,505 and $14,941 in 2017 and $5,042 and $15,171 in 2016.	75,927	79,425	221,285	234,269
Real estate taxes	64,160	64,133	186,173	187,931
Ground rent	8,307	8,338	24,923	24,953
Interest expense, net of interest income	65,634	72,565	196,112	256,326
Amortization of deferred financing costs	4,008	4,815	12,201	20,180
Depreciation and amortization	91,728	112,665	318,916	717,015
Transaction related costs	186	2,593	365	5,987
Marketing, general and administrative	23,963	25,458	72,362	73,974
Total expenses	333,913	369,992	1,032,337	1,520,635
Income (loss) before equity in net income (loss) from unconsolidated joint ventures, equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain (loss) on sale of real estate, net, depreciable real estate reserves, and gain (loss) on sale of investment in marketable securities	40,687	46,689	117,794	(30,896)
Equity in net income (loss) from unconsolidated joint ventures	4,078	(3,968)	14,104	11,969
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	1,030	225	16,166	43,588
Gain (loss) on sale of real estate, net	0	397	(3,256)	210,750
Depreciable real estate reserves	0	0	(85,336)	(10,387)
Gain (loss) on sale of investment in marketable securities	0	0	3,262	(83)
Net income	45,795	43,343	62,734	224,941
Net (income) loss attributable to noncontrolling interests:
Noncontrolling interests in the Operating Partnership			(2,707)
Noncontrolling interests in other partnerships	1,474	(836)	18,179	(6,245)
Preferred units distributions	(2,850)	(2,854)	(8,551)	(8,382)
Net income (loss) attributable to SL Green/SLGOP	44,419	39,653	72,362	210,314
Perpetual preferred unit distributions	(3,738)	(3,738)	(11,213)	(11,213)
Net income attributable to SLGOP common unitholders	40,681	35,915	61,149	199,101
Amounts attributable to SL Green common stockholders:
Income (loss) before depreciable real estate reserves and gains (losses) on sale	39,651	35,293	133,575	(44,850)
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	1,030	225	16,166	43,588
Gain (loss) on sale of real estate, net	0	397	(3,256)	210,750
Depreciable real estate reserves	$ 0	$ 0	$ (85,336)	$ (10,387)
Basic earnings per share:
Income (loss) before depreciable real estate reserves and gains (losses) on sale (in dollars per share)	$ 0.39	$ 0.34	$ 1.28	$ (0.43)
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (in dollars per share)	0.01	0	0.16	0.42
Gain (loss) on sale of real estate, net	0	0	(0.03)	2.02
Depreciable real estate reserves	0	0	(0.82)	(0.10)
Net income attributable to SLGOP common unitholders (usd per share)	0.40	0.34	0.59	1.91
Diluted earnings per share:
Income (loss) before depreciable real estate reserves and gains (losses) on sale (in dollars per share)	0.39	0.34	1.28	(0.43)
Equity in net gain on sale of interest in unconsolidated joint venture/real estate (in dollars per share)	0.01	0	0.16	0.42
Gain on sale of real estate (in dollars per share)	0	0	(0.03)	2.01
Depreciable real estate reserves (in dollars per share)	0	0	(0.82)	(0.10)
Net income attributable to SLGOP common unitholders (usd per share)	0.40	0.34	0.59	1.90
Dividends per share/unit (usd per share)	$ 0.775	$ 0.72	$ 2.325	$ 2.16
Basic weighted average common shares outstanding (in shares)	102,326	104,730	104,001	104,412
Basic weighted average common units outstanding (in shares)	102,326	104,730	104,001	104,412
Diluted weighted average common units and common unit equivalents outstanding (in shares)	102,570	105,143	104,280	104,761

Consolidated Statements of Ope5

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating expenses, paid to related parties	$ 5,505	$ 5,042	$ 14,941	$ 15,171
SL Green Operating Partnership
Operating expenses, paid to related parties	$ 5,505	$ 5,042	$ 14,941	$ 15,171

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 45,795	$ 43,343	$ 62,734	$ 224,941
Other comprehensive loss:
Change in net unrealized gain on derivative instruments, including SL Green's/SLGOP's share of joint venture net unrealized (loss) gain on derivative instruments	(217)	2,632	(3,812)	(4,682)
Change in unrealized gain on marketable securities	44	(30)	(4,443)	(900)
Other comprehensive (loss) income	(173)	2,602	(8,255)	(5,582)
Comprehensive income	45,622	45,945	54,479	219,359
Net (income) loss attributable to noncontrolling interests and preferred units distributions	(3,188)	(5,353)	6,921	(22,798)
Net loss (income) attributable to noncontrolling interests	1,474	(836)	18,179	(6,245)
Other comprehensive loss attributable to noncontrolling interests	4	(118)	303	257
Comprehensive income attributable to SL Green/SLGOP	42,438	40,474	61,703	196,818
SL Green Operating Partnership
Net income	45,795	43,343	62,734	224,941
Other comprehensive loss:
Change in net unrealized gain on derivative instruments, including SL Green's/SLGOP's share of joint venture net unrealized (loss) gain on derivative instruments	(217)	2,632	(3,812)	(4,682)
Change in unrealized gain on marketable securities	44	(30)	(4,443)	(900)
Other comprehensive (loss) income	(173)	2,602	(8,255)	(5,582)
Comprehensive income	45,622	45,945	54,479	219,359
Net loss (income) attributable to noncontrolling interests	1,474	(836)	18,179	(6,245)
Other comprehensive loss attributable to noncontrolling interests	4	(118)	303	257
Comprehensive income attributable to SL Green/SLGOP	$ 47,100	$ 44,991	$ 72,961	$ 213,371

Consolidated Statement of Equit

Consolidated Statement of Equity (Unaudited) - 9 months ended Sep. 30, 2017 - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In-Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Noncontrolling Interests
Beginning Balance at Dec. 31, 2016	$ 7,750,911	$ 221,932	$ 1,017	$ 5,624,545	$ (124,049)	$ 22,137	$ 1,578,893	$ 426,436
Beginning Balance (in shares) at Dec. 31, 2016			100,562
Increase (Decrease) in Stockholders' Equity
Net income (loss)	51,476						69,655	(18,179)
Other comprehensive loss	(7,952)					(7,952)
Preferred dividends	(11,213)						(11,213)
DRSPP proceeds (in shares)			2
DRSPP proceeds	185			185
Conversion of units of the Operating Partnership to common stock (in shares)			142
Conversion of units of the Operating Partnership to common stock	15,353		$ 1	15,352
Reallocation of noncontrolling interest in the Operating Partnership	2,669						2,669
Equity component of repurchased exchangeable senior notes	(27,969)			(27,969)
Deferred compensation plan and stock awards, net (in shares)			(6)
Deferred compensation plan and stock awards, net	(1,959)			(1,959)
Amortization of deferred compensation plan	22,014			22,014
Repurchases of common stock (in shares)			(3,400)
Repurchases of common stock	(349,991)		$ (34)	(349,957)
Proceeds from stock options exercised (in shares)			146
Proceeds from stock options exercised	12,290		$ 1	12,289
Contributions to consolidated joint venture interests	33,202							33,202
Deconsolidation of partially owned entity	(30,203)							(30,203)
Cash distributions to noncontrolling interests	(45,089)							(45,089)
Cash distributions declared ($2.325 per common share, none of which represented a return of capital for federal income tax purposes)	(229,672)						(229,672)
Ending Balance at Sep. 30, 2017	$ 7,184,052	$ 221,932	$ 985	$ 5,294,500	$ (124,049)	$ 14,185	$ 1,410,332	$ 366,167
Ending Balance (in shares) at Sep. 30, 2017			97,446

Consolidated Statement of Equi8

Consolidated Statement of Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Stockholders' Equity [Abstract]
Cash distribution declared, per common share (in dollars per share)	$ 0.775	$ 0.72	$ 2.325	$ 2.16

Consolidated Statement of Capit

Consolidated Statement of Capital (Unaudited) shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)shares
Increase (Decrease) in Partner's Capital
DRSPP proceeds	$ 185
Conversion of common units	15,353
Reallocation of noncontrolling interests in the operating partnership	2,669
Equity component of repurchased exchangeable senior notes	(27,969)
Deferred compensation plan and stock awards, net	(1,959)
Amortization of deferred compensation plan	22,014
Repurchases of common stock	(349,991)
Contribution to consolidated joint venture interests	33,202
Deconsolidation of partially owned entity	(30,203)
Cash distributions to noncontrolling interests	$ (45,089)
Common Stock
Increase (Decrease) in Partner's Capital
DRSPP proceeds (in shares) | shares	2
Conversion of common units	$ 1
Deferred compensation plan and stock awards, net (in shares) | shares	(6)
Repurchases of common stock (in shares) | shares	(3,400)
Repurchases of common stock	$ (34)
Contributions - proceeds from stock options exercised (in shares) | shares	146
Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Contribution to consolidated joint venture interests	$ 33,202
Deconsolidation of partially owned entity	(30,203)
Cash distributions to noncontrolling interests	(45,089)
SL Green Operating Partnership
Increase (Decrease) in Partner's Capital
Beginning Balance	7,750,911
Net income (loss)	51,476
Other comprehensive loss	(7,952)
Preferred distributions	(11,213)
DRSPP proceeds	185
Conversion of common units	15,353
Reallocation of noncontrolling interests in the operating partnership	2,669
Equity component of repurchased exchangeable senior notes	(27,969)
Deferred compensation plan and stock awards, net	(1,959)
Amortization of deferred compensation plan	22,014
Repurchases of common stock	(349,991)
Contribution to consolidated joint venture interests	33,202
Deconsolidation of partially owned entity	(30,203)
Contributions - proceeds from stock options exercised	12,290
Cash distributions to noncontrolling interests	(45,089)
Cash distributions declared ($2.325 per common unit, none of which represented a return of capital for federal income tax purposes)	(229,672)
Ending Balance	7,184,052
SL Green Operating Partnership | Preferred Units
Increase (Decrease) in Partner's Capital
Beginning Balance	221,932
Ending Balance	221,932
SL Green Operating Partnership | Common Stock | Partners' Interest
Increase (Decrease) in Partner's Capital
Beginning Balance	$ 7,080,406
Beginning Balance (units) | shares	100,562
Net income (loss)	$ 69,655
Preferred distributions	$ (11,213)
DRSPP proceeds (in shares) | shares	2
DRSPP proceeds	$ 185
Conversion of common units (in shares) | shares	142
Conversion of common units	$ 15,353
Reallocation of noncontrolling interests in the operating partnership	2,669
Equity component of repurchased exchangeable senior notes	$ (27,969)
Deferred compensation plan and stock awards, net (in shares) | shares	(6)
Deferred compensation plan and stock awards, net	$ (1,959)
Amortization of deferred compensation plan	$ 22,014
Repurchases of common stock (in shares) | shares	(3,400)
Repurchases of common stock	$ (349,991)
Contributions - proceeds from stock options exercised (in shares) | shares	146
Contributions - proceeds from stock options exercised	$ 12,290
Cash distributions declared ($2.325 per common unit, none of which represented a return of capital for federal income tax purposes)	(229,672)
Ending Balance	$ 6,581,768
Ending Balance (units) | shares	97,446
SL Green Operating Partnership | Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Partner's Capital
Beginning Balance	$ 22,137
Other comprehensive loss	(7,952)
Ending Balance	14,185
SL Green Operating Partnership | Noncontrolling Interests
Increase (Decrease) in Partner's Capital
Beginning Balance	426,436
Net income (loss)	(18,179)
Contribution to consolidated joint venture interests	33,202
Deconsolidation of partially owned entity	(30,203)
Cash distributions to noncontrolling interests	(45,089)
Ending Balance	$ 366,167

Consolidated Statement of Cap10

Consolidated Statement of Capital (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Cash distribution declared, per common share (in dollars per share)	$ 0.775	$ 0.72	$ 2.325	$ 2.16
SL Green Operating Partnership
Cash distribution declared, per common share (in dollars per share)	$ 0.775	$ 0.72	$ 2.325	$ 2.16

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016
Operating Activities
Net income		$ 62,734	$ 224,941
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		331,117	737,195
Equity in net income from unconsolidated joint ventures		(14,104)	(11,969)
Distributions of cumulative earnings from unconsolidated joint ventures		19,609	19,311
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate		(16,166)	(43,588)
Depreciable real estate reserves		85,336	10,387
Loss (gain) on sale of real estate, net		3,256	(210,750)
(Gain) loss on sale of investments in marketable securities		(3,262)	83
Deferred rents receivable		(33,523)	40,056
Other non-cash adjustments	[1]	18,423	(155,558)
Changes in operating assets and liabilities:
Restricted cash—operations		6,520	(12,855)
Tenant and other receivables		(2,318)	2,714
Related party receivables		(8,238)	(4,167)
Deferred lease costs		(31,479)	(47,036)
Other assets		(58,068)	(30,899)
Accounts payable, accrued expenses, other liabilities and security deposits		1,423	(28,089)
Deferred revenue and land leases payable		55,361	19,016
Net cash provided by operating activities		416,621	508,792
Investing Activities
Acquisitions of real estate property		(25,114)	(38,005)
Additions to land, buildings and improvements		(251,158)	(269,182)
Escrowed cash—capital improvements/acquisition deposits/deferred purchase price		17,431	85,983
Investments in unconsolidated joint ventures		(112,697)	(69,422)
Distributions in excess of cumulative earnings from unconsolidated joint ventures		279,478	171,472
Net proceeds from disposition of real estate/joint venture interest		116,983	2,419,841
Proceeds from sale or redemption of marketable securities		55,129	6,868
Purchases of marketable securities		0	(23,062)
Other investments		46,955	8,232
Origination of debt and preferred equity investments		(935,724)	(554,803)
Repayments or redemption of debt and preferred equity investments		707,676	667,251
Net cash (used in) provided by investing activities		(101,041)	2,405,173
Financing Activities
Proceeds from mortgages and other loans payable		779,650	256,207
Repayments of mortgages and other loans payable		(706,056)	(1,786,034)
Proceeds from revolving credit facility and senior unsecured notes		1,447,800	1,260,300
Repayments of revolving credit facility and senior unsecured notes		(1,270,804)	(2,269,604)
Proceeds from stock options exercised and DRIP issuance		12,475	12,404
Repurchase of common stock		(349,991)	0
Redemption of preferred stock		(125)	(2,999)
Distributions to noncontrolling interests in other partnerships		(45,089)	(11,023)
Contributions from noncontrolling interests in other partnerships		33,202	2,019
Distributions to noncontrolling interests in the Operating Partnership		(10,639)	(9,245)
Dividends / Distributions paid on common and preferred stock / units		(251,701)	(234,801)
Other obligations related to loan participations		16,737	59,150
Deferred loan costs and capitalized lease obligation		(8,993)	(39,842)
Net cash used in financing activities		(353,534)	(2,763,468)
Net (decrease) increase in cash and cash equivalents		(37,954)	150,497
Cash and cash equivalents at beginning of year		279,443	255,399
Cash and cash equivalents at end of period		241,489	405,896
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of units in the Operating Partnership		23,273	51,647
Redemption of units in the Operating Partnership for stock		15,352	12,746
Derivative instruments at fair value		7,362	0
Exchange of debt investment for equity in joint venture		0	68,581
Issuance of preferred units relating to a real estate acquisition		0	22,793
Tenant improvements and capital expenditures payable		8,926	4,281
Fair value adjustment to noncontrolling interest in Operating Partnership		2,669	4,959
Deconsolidation of subsidiaries		328,643	1,173,570
Transfer of assets related to assets held for sale		273,455	2,048,376
Transfer of liabilities related to assets held for sale		1,290	1,677,528
Deferred leasing payable		810	1,208
Transfer of assets related to assets held for sale		11,158	22,179
Issuance of SLG's common stock to consolidated joint venture		0
SL Green Operating Partnership
Operating Activities
Net income		62,734	224,941
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		331,117	737,195
Equity in net income from unconsolidated joint ventures		(14,104)	(11,969)
Distributions of cumulative earnings from unconsolidated joint ventures		19,609	19,311
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate		(16,166)	(43,588)
Depreciable real estate reserves		85,336	10,387
Loss (gain) on sale of real estate, net		3,256	(210,750)
(Gain) loss on sale of investments in marketable securities		(3,262)	83
Deferred rents receivable		(33,523)	40,056
Other non-cash adjustments	[1]	18,423	(155,558)
Changes in operating assets and liabilities:
Restricted cash—operations		6,520	(12,855)
Tenant and other receivables		(2,318)	2,714
Related party receivables		(8,238)	(4,167)
Deferred lease costs		(31,479)	(47,036)
Other assets		(58,068)	(30,899)
Accounts payable, accrued expenses, other liabilities and security deposits		1,423	(28,089)
Deferred revenue and land leases payable		55,361	19,016
Net cash provided by operating activities		416,621	508,792
Investing Activities
Acquisitions of real estate property		(25,114)	(38,005)
Additions to land, buildings and improvements		(251,158)	(269,182)
Escrowed cash—capital improvements/acquisition deposits/deferred purchase price		17,431	85,983
Investments in unconsolidated joint ventures		(112,697)	(69,422)
Distributions in excess of cumulative earnings from unconsolidated joint ventures		279,478	171,472
Net proceeds from disposition of real estate/joint venture interest		116,983	2,419,841
Proceeds from sale or redemption of marketable securities		55,129	6,868
Purchases of marketable securities		0	(23,062)
Other investments		46,955	8,232
Origination of debt and preferred equity investments		(935,724)	(554,803)
Repayments or redemption of debt and preferred equity investments		707,676	667,251
Net cash (used in) provided by investing activities		(101,041)	2,405,173
Financing Activities
Proceeds from mortgages and other loans payable		779,650	256,207
Repayments of mortgages and other loans payable		(706,056)	(1,786,034)
Proceeds from revolving credit facility and senior unsecured notes		1,447,800	1,260,300
Repayments of revolving credit facility and senior unsecured notes		(1,270,804)	(2,269,604)
Proceeds from stock options exercised and DRIP issuance		12,475	12,404
Repurchase of common stock		(349,991)	0
Redemption of preferred stock		(125)	(2,999)
Distributions to noncontrolling interests in other partnerships		(45,089)	(11,023)
Contributions from noncontrolling interests in other partnerships		33,202	2,019
Dividends / Distributions paid on common and preferred stock / units		(262,340)	(244,046)
Other obligations related to loan participations		16,737	59,150
Deferred loan costs and capitalized lease obligation		(8,993)	(39,842)
Net cash used in financing activities		(353,534)	(2,763,468)
Net (decrease) increase in cash and cash equivalents		(37,954)	150,497
Cash and cash equivalents at beginning of year		279,443	255,399
Cash and cash equivalents at end of period		241,489	405,896
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of units in the Operating Partnership		23,273	51,647
Redemption of units in the Operating Partnership for stock		15,352	12,746
Derivative instruments at fair value		7,362	0
Exchange of debt investment for equity in joint venture		0	68,581
Issuance of preferred units relating to a real estate acquisition		0	22,793
Tenant improvements and capital expenditures payable		8,926	4,281
Fair value adjustment to noncontrolling interest in Operating Partnership		2,669	4,959
Deconsolidation of subsidiaries		328,643	1,173,570
Transfer of assets related to assets held for sale		273,455	2,048,376
Transfer of liabilities related to assets held for sale		1,290	1,677,528
Deferred leasing payable		810	1,208
Transfer of assets related to assets held for sale		$ 11,158	$ 22,179
[1]	Included in Other non-cash adjustments is $172.4 million for the nine months ended September 30, 2016 for the amortization of the below-market lease at 388-390 Greenwich Street as a result of the tenant exercising their option to purchase the property and entering into an agreement to accelerate the sale.

Consolidated Statements of Ca12

Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) - 388-390 Greenwich Street $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Amortization of below market lease	$ 172.4
SL Green Operating Partnership
Amortization of below market lease	$ 172.4

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 , noncontrolling investors held, in the aggregate, a 4.45% 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". Reckson Associates Realty Corp., or Reckson, and Reckson Operating Partnership, L.P., or ROP, are wholly-owned subsidiaries of SL Green Realty Corp. As of September 30, 2017 , we owned the following interests in properties in the New York Metropolitan area, primarily in midtown Manhattan. Our investments in the New York Metropolitan area also include investments in Brooklyn, Long Island, Westchester County, Connecticut and New Jersey, which are collectively known as the Suburban properties: Consolidated Unconsolidated Total Location Property Number of Properties Approximate Square Feet (unaudited) Number of Properties Approximate Square Feet (unaudited) Number of Properties Approximate Square Feet (unaudited) Weighted Average Occupancy (1) (unaudited) Commercial: Manhattan Office 24 16,054,606 7 6,558,139 31 22,612,745 93.4 % Retail 4 (2) 302,583 9 347,970 13 650,553 94.5 % Development/Redevelopment 7 158,985 4 770,514 11 929,499 59.9 % Fee Interest 1 176,530 1 — 2 176,530 100.0 % 36 16,692,704 21 7,676,623 57 24,369,327 92.2 % Suburban Office 22 (3)(4) 3,608,800 2 640,000 24 4,248,800 83.1 % Retail 1 52,000 — — 1 52,000 100.0 % Development/Redevelopment 1 1,000 1 — 2 1,000 100.0 % 24 3,661,800 3 640,000 27 4,301,800 83.3 % Total commercial properties 60 20,354,504 24 8,316,623 84 28,671,127 90.8 % Residential: Manhattan Residential 3 (2) 472,105 12 2,656,856 15 3,128,961 86.4 % Suburban Residential — — — — — — — % Total residential properties 3 472,105 12 2,656,856 15 3,128,961 86.4 % Total portfolio (2)(3) 63 20,826,609 36 10,973,479 99 31,800,088 90.4 % (1) The weighted average occupancy for commercial properties represents the total occupied square feet divided by total square footage at acquisition. The weighted average occupancy for residential properties represents the total occupied units divided by total available units. (2) As of September 30, 2017 , we owned a building at 315 West 33rd Street, also known as The Olivia, that was comprised of approximately 270,132 square feet (unaudited) of retail space and approximately 222,855 square feet (unaudited) of residential space. For the purpose of this report, we have included this building in the number of retail properties we own. However, we have included only the retail square footage in the retail approximate square footage, and have listed the balance of the square footage as residential square footage. (3) Includes the properties at 16 Court Street in Brooklyn, New York, and 125 Chubb Avenue in Lyndhurst, New Jersey which are classified as held for sale at September 30, 2017. The sales closed in October 2017. As of September 30, 2017 , we also managed an approximately 336,000 square foot (unaudited) office building owned by a third party and held debt and preferred equity investments with a book value of $2.2 billion , including $0.1 billion of debt and preferred equity investments and other financing receivables that are included in other 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. 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 September 30, 2017 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, 2017 . 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, 2016 of the Company and the Operating Partnership. The consolidated balance sheet at December 31, 2016 has been derived from the audited financial statements as of that date but do not include all the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
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 variable interest entity, or 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 On a periodic basis, we assess whether there are any indications that the value of our real estate properties may be other than temporarily 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 calculated fair value of the property. We also evaluate our real estate properties for potential impairment when a real estate property has been classified as held for sale. Real estate assets held for sale are valued at the lower of either their carrying value or fair value less costs to sell. We do not believe that there were any indicators of impairment at any of our consolidated properties at September 30, 2017 . We recorded no depreciable real estate reserves for the three months ended September 30, 2017 , and aggregate depreciable real estate reserves of $85.3 million for the nine months ended September 30, 2017 . See Note 4, "Property Dispositions". 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 three 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 one to 14 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 one to 14 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 and capitalization 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. We recognized $4.6 million and $15.8 million of rental revenue for the three and nine months ended September 30, 2017 , and $0.2 million and $191.4 million of rental revenue for the three and nine months ended September 30, 2016 for the amortization of aggregate below-market leases in excess of above-market leases and a reduction in lease origination costs, resulting from the allocation of the purchase price of the applicable properties. Included in rental revenue is zero and $172.4 million for the three and nine months ended September 30, 2016 , for the amortization of the below-market lease at 388-390 Greenwich Street as a result of the tenant exercising their option to purchase the property and entering into an agreement to accelerate the sale. For the three and nine months ended September 30, 2017 , we recognized as a reduction to interest expense the amortization of above-market rate mortgages of $0.0 million and $0.8 million , respectively. For the three and nine months ended September 30, 2016 , we recognized as a reduction to interest expense the amortization of the above-market rate mortgages assumed of $0.7 million and $2.0 million , respectively. The following summarizes our identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases) as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Identified intangible assets (included in other assets): Gross amount $ 474,493 $ 651,099 Accumulated amortization (398,047 ) (410,930 ) Net (1) $ 76,446 $ 240,169 Identified intangible liabilities (included in deferred revenue): Gross amount $ 639,511 $ 655,930 Accumulated amortization (474,365 ) (464,749 ) Net (1) $ 165,146 $ 191,181 (1) As of September 30, 2017 and December 31, 2016, $3.9 million and none , respectively and $1.1 million and none , respectively, of net intangible assets and net intangible liabilities, were reclassified to assets held for sale and liabilities related to assets held for sale. 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 September 30, 2017 , 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 Accounting Standards Codification, or ASC, 820-10, with the net unrealized gains or losses reported as a component of accumulated other comprehensive income or loss. Any unrealized losses that are determined to be other-than-temporary are recognized in earnings up to their credit component. The cost of bonds and marketable securities sold is determined using the specific identification method. At September 30, 2017 and December 31, 2016 , we held the following marketable securities (in thousands): September 30, 2017 December 31, 2016 Equity marketable securities $ — $ 48,315 Commercial mortgage-backed securities 28,802 36,795 Total marketable securities available-for-sale $ 28,802 $ 85,110 The cost basis of the commercial mortgage-backed securities was $27.5 million and $36.0 million at September 30, 2017 and December 31, 2016 , respectively. These securities mature at various times through 2049. We held no equity marketable securities as of September 30, 2017 . The cost basis of the equity marketable securities was $43.3 million at December 31, 2016 . During the three and nine months ended September 30, 2017 , we disposed of marketable securities for aggregate net proceeds of $0.8 million and $55.2 million , respectively. During the three and nine months ended September 30, 2016 , we disposed of marketable securities for aggregate net proceeds of $1.7 million and $6.9 million , respectively. 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 the joint ventures' projected discounted cash flows. We do not believe that the values of any of our equity investments were impaired at September 30, 2017 . Reserve for Possible Credit Losses The expense for possible credit losses in connection with debt and preferred equity investments is the charge to earnings to increase the allowance for possible credit losses to the level that we estimate to be adequate, based on Level 3 data, considering delinquencies, loss experience and collateral quality. Other factors considered include geographic trends, product diversification, the size of the portfolio and current economic conditions. Based upon these factors, we establish a provision for possible credit loss on each individual investment. When it is probable that we will be unable to collect all amounts contractually due, the investment is considered impaired. Where impairment is indicated on an investment that is held to maturity, a valuation allowance is measured based upon the excess of the recorded investment amount over the net fair value of the collateral. Any deficiency between the carrying amount of an asset and the calculated value of the collateral is charged to expense. We continue to assess or adjust our estimates based on circumstances of a loan and the underlying collateral. If additional information reflects increased recovery of our investment, we will adjust our reserves accordingly. There were no loan reserves recorded during the three and nine months ended September 30, 2017 and 2016 . 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 SL Green's 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 SL Green's 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. Pursuant to amendments to the Code that became effective January 1, 2001, we have elected, and may elect in the future, to treat certain of our existing or newly created 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 and nine months ended September 30, 2017 , we recorded Federal, state and local tax provisions of $0.1 million and $2.8 million , respectively. 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 ongoing credit evaluations 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 source of funds to offset the economic costs associated with lost revenue and the costs associated with re-tenanting a space. The properties in our real estate portfolio are primarily located in Manhattan. We also have properties located in Brooklyn, Long Island, Westchester County, Connecticut and New Jersey. The tenants located in our buildings operate in various industries. Other than two tenants, Credit Suisse Securities (USA), Inc. and Viacom International, Inc., who account for 8.8% and 6.7% 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 September 30, 2017 . For the three months ended September 30, 2017 , 8.9% , 6.3% , 6.2% , and 5.4% of our share of cash rent, including our share of joint venture annualized rent, was attributable to 1515 Broadway, 11 Madison Avenue, 1185 Avenue of the Americas, and 420 Lexington Avenue, respectively. Our share of annualized cash rent for all other properties was below 5.0% . Reclassification Certain prior year balances have been reclassified to conform to our current year presentation. Accounting Standards Updates In August 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-12, Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities. The amendments in the new standard will permit more flexibility in hedging interest rate risk for both variable rate and fixed rate financial instruments. The standard will also enhance the presentation of hedge results in the financial statements. The guidance is effective for fiscal years beginning after December 15, 2018 and early adoption is permitted. The Company has not yet adopted the guidance, and does not expect a material impact on the Company’s consolidated financial statements when the new standard is implemented. In May 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-09, Compensation - Stock Compensation (Topic 718), Scope of Modification Accounting. The guidance clarifies the changes to the terms or conditions of a share-based payment award that require an entity to apply modification accounting in Topic 718. The guidance is effective for fiscal years beginning after December 15, 2017 and early adoption is permitted. The Company has not yet adopted the guidance. In February 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-05 to clarify the scope of Subtopic 610-20 as well as provide guidance on accounting for partial sales of nonfinancial assets. Subtopic 610-20 was issued in May 2014 as part of ASU 2014-09. The Company anticipates adopting this guidance January 1, 2018, and applying the modified retrospective approach. The Company is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In January, 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. The guidance clarifies the definition of a business and provides guidance to assist with determining whether transactions should be accounted for as acquisitions of assets or businesses. The main provision is that an acquiree is not a business if substantially all of the fair value of the gross assets is concentrated in a single identifiable asset or group of assets. The Company adopted the guidance on the issuance date effective January 5, 2017. The Company expects that most of our real estate acquisitions will be considered asset acquisitions under the new guidance and that transaction costs will be capitalized to the investment basis which is then subject to a purchase price allocation based on relative fair value. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The guidance will require entities to show the changes on the total cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between these items on the statement of cash flows. The guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The ASU provides final guidance on eight cash flow issues, including debt prepayment or debt extinguishment costs, contingent consideration payments made after a business combination, distributions received from equity method investees, separately identifiable cash flows and application of the predominance principle, and others. The amendments in the ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company adopted the guidance effective January 1, 2017 and there was no impact on the Company’s consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The guidance changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance replaces the current ‘incurred loss’ model with an ‘expected loss’ approach. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted after December 2018. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The guidance simplifies the accounting for share-based payment award transactions including: income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The guidance is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted. The Company adopted the guidance effective January 1, 2017 and there was no material impact on the Company’s consolidated financial statements. In March 2016, the FASB issued ASU 2016-07, Investments Equity Method and Joint Ventures (Topic 323). The guidance eliminates the requirement that an entity retroactively adopt the equity method of accounting if an investment qualifies for use of the equity method as a result of an increase in the level of ownership or degree of influence. The amendments require that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor’s previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. The Company adopted the guidance effective January 1, 2017 and there was no impact on the Company’s consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases. The guidance requires lessees to recognize lease assets and lease liabilities for those leases classified as operating leases under the previous standard. Depending on the lease classification, lessees will recognize expense based on the effective interest method for finance leases or on a straight-line basis for operating leases. The accounting applied by a lessor is largely unchanged from that applied under the previous standard. One of the impacts on the Company will be the presentation and disclosure in the financial statements of non-lease components such as charges to tenants for a building’s operating expenses. The non-lease components will be presented separately from the lease components in both the Consolidated Statements of Operations and Consolidated Balance Sheets. Another impact is the measurement and presentation of ground leases under which the Company is lessee. The Company is required to record a liability for the obligation to make payments under the lease and an asset for the right to use the underlying asset during the lease term and will also apply the new expense recognition requirements given the lease classification. The Company is currently quantifying these impacts. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The Company anticipates adopting this guidance January 1, 2019 and will apply the modified retrospective approach. In January 2016, the FASB issued ASU 2016-01 (Subtopic 825-10), Recognition and Measurement of Financial Assets and Financial Liabilities. The guidance requires entities to measure equity investments that do not result in consolidation and are not accounted for under the equity method at fair value and to record changes in instruments-specific credit risk for financial liabilities measured under the fair value option in other comprehensive income. The guidance is effective for fiscal years beginning after December 15, 2017, and for interim periods therein. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In May 2014, the FASB issued a new comprehensive revenue recognition guidance which requires us to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods and services (ASU 2014-09). The FASB also issued implementation guidance in March 2016, April 2016 and May 2016 - ASU’s 2016-08, 2016-10 and 2016-12, respectively. These ASUs are effective for annual and interim periods beginning after December 15, 2017. The Company will adopt this guidance January 1, 2018. Since the Company’s revenue is related to leasing activities, the adoption of this guidance will not have a material impact on the consolidated financial statements. The new guidance is applicable to service contracts with joint ventures for which the Company earns property management fees, leasing commissions and development and construction fees. The adoption of this new guidance does not change the accounting for these fees as the pattern of recognition of revenue does not change with the new guidance. We will continue to recognize revenue over time on these contracts because the customer simultaneously receives and consumes the benefits provided by our performance. Thus, the analysis of our contracts under the new revenue recognition standard is consistent with our current revenue recognition model.

Property Acquisitions

Property Acquisitions	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Property Acquisitions	Property Acquisitions During the nine months ended September 30, 2017 , we did not acquire any properties from a third party.

Properties Held for Sale and Pr

Properties Held for Sale and Property Dispositions	9 Months Ended
	Sep. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Properties Held for Sale and Property Dispositions	Properties Held for Sale and Property Dispositions Properties Held for Sale During the three months ended September 30, 2017 , we entered into an agreement to sell the property at 16 Court Street in Brooklyn, New York, for a gross sales price of $171.0 million . As of September 30, 2017, 16 Court Street in Brooklyn, New York and 125 Chubb in Lyndhurst, New Jersey were held for sale. We closed on the sale of both properties in October 2017. Property Dispositions The following table summarizes the properties sold during the nine months ended September 30, 2017 : Property Disposition Date Property Type Approximate Square Feet Sales Price (1) (in millions) Gain (loss) (2) (in millions) 885 Third Avenue (3) February 2016 Fee Interest 607,000 $ 453.0 $ (8.8 ) 520 White Plains Road April 2017 Office 180,000 21.0 (14.6 ) 102 Greene Street (4) April 2017 Retail 9,200 43.5 4.9 680-750 Washington Boulevard July 2017 Office 325,000 97.0 (44.2 ) (1) Sales price represents the gross sales price for a property or the gross asset valuation for interests in a property. (2) The gain on sale for 102 Greene Street is net of $0.9 million in employee compensation awards accrued in connection with the realization of the investment gain as a bonus to certain employees that were instrumental in realizing the gain on sale. Additionally, gain on sale amounts do not include adjustments for expenses recorded in subsequent periods. (3) In February 2016, we closed on the sale of 885 Third Avenue. The sale did not meet the criteria for sale accounting and as a result the property remained on our consolidated financial statements until the criteria was met in April 2017. (4) In April 2017, we closed on the sale of a 90% interest 102 Greene Street and had subsequently accounted for our interest in the property as an investment in unconsolidated joint ventures. We sold the remaining 10% interest in September 2017. See Note 6, "Investments in Unconsolidated Joint Ventures".

Debt and Preferred Equity Inves

Debt and Preferred Equity Investments	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Debt and Preferred Equity Investments	Debt and Preferred Equity Investments Below is the rollforward analysis of the activity relating to our debt and preferred equity investments as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Balance at beginning of period (1) $ 1,640,412 $ 1,670,020 Debt Investment Originations/Accretion (2) 944,494 1,009,176 Preferred Equity Investment Originations/Accretion (2) 144,013 5,698 Redemptions/Sales/Syndications/Amortization (3) (708,180 ) (1,044,482 ) Balance at end of period (1) $ 2,020,739 $ 1,640,412 (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 did not meet the conditions for sale accounting are included in other assets and other liabilities on the consolidated balance sheets. Debt Investments As of September 30, 2017 and December 31, 2016 , we held the following debt investments with an aggregate weighted average current yield of 9.49% , excluding our investment in Two Herald Square, at September 30, 2017 (in thousands): Loan Type September 30, 2017 Future Funding Obligations September 30, 2017 Senior September 30, 2017 (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Fixed Rate Investments: Mortgage/Jr. Mortgage Loan (3) $ — $ — $ 250,164 $ — April 2017 Mortgage Loan (4) — — 26,352 26,311 February 2019 Mortgage Loan — — 275 380 August 2019 Mezzanine Loan (5a) — 1,160,000 201,757 — March 2020 Mezzanine Loan — 15,000 3,500 3,500 September 2021 Mezzanine Loan — 147,000 24,909 — April 2022 Mezzanine Loan — 87,595 12,697 12,692 November 2023 Mezzanine Loan (5b) — 115,000 12,930 12,925 June 2024 Mezzanine Loan — 95,000 30,000 30,000 January 2025 Mezzanine Loan — 340,000 15,000 15,000 November 2026 Mezzanine Loan — 1,657,500 55,250 — June 2027 Mezzanine Loan (6) — — — 66,129 Jr. Mortgage Participation/Mezzanine Loan (7) — — — 193,422 Total fixed rate $ — $ 3,617,095 $ 632,834 $ 360,359 Floating Rate Investments: Mortgage/Mezzanine Loan (8) 622 — 23,372 20,423 October 2017 Mezzanine Loan (5c) — 85,000 15,340 15,141 December 2017 Mezzanine Loan (5d) — 65,000 14,832 14,656 December 2017 Mezzanine Loan (5e) 795 — 15,132 15,051 December 2017 Mortgage/Mezzanine Loan (9) — 125,000 29,966 29,998 January 2018 Mezzanine Loan — 40,000 19,964 19,913 April 2018 Jr. Mortgage Participation — 117,808 34,899 34,844 April 2018 Mezzanine Loan 523 20,523 10,916 10,863 August 2018 Mortgage/Mezzanine Loan — — 19,914 19,840 August 2018 Mortgage Loan — 65,000 14,935 14,880 August 2018 Loan Type September 30, 2017 Future Funding Obligations September 30, 2017 Senior September 30, 2017 (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Mortgage/Mezzanine Loan (10) — — 16,957 16,960 September 2018 Mezzanine Loan — 37,500 14,801 14,648 September 2018 Mezzanine Loan 2,325 45,025 34,782 34,502 October 2018 Mezzanine Loan — 335,000 74,683 74,476 November 2018 Mezzanine Loan — 33,000 26,907 26,850 December 2018 Mezzanine Loan 1,050 171,939 58,598 56,114 December 2018 Mezzanine Loan 8,267 289,621 71,067 63,137 December 2018 Mezzanine Loan 5,197 229,084 74,314 64,505 December 2018 Mezzanine Loan — 45,000 12,156 12,104 January 2019 Mortgage/Mezzanine Loan (5f) 30,101 — 158,757 — January 2019 Mezzanine Loan 6,081 24,086 7,812 5,410 January 2019 Mezzanine Loan — 38,000 21,927 21,891 March 2019 Mezzanine Loan 279 173,700 36,936 — April 2019 Mezzanine Loan — 265,000 24,798 24,707 April 2019 Mortgage/Jr. Mortgage Participation Loan 29,661 194,094 69,705 65,554 August 2019 Mezzanine Loan 2,034 187,500 37,835 37,322 September 2019 Mortgage/Mezzanine Loan 49,933 — 130,350 111,819 September 2019 Mortgage/Mezzanine Loan 30,494 — 38,934 33,682 January 2020 Mezzanine Loan (11) 6,794 537,748 72,597 125,911 January 2020 Mezzanine Loan 7,164 33,587 10,988 — July 2020 Jr. Mortgage Participation/Mezzanine Loan — 60,000 15,627 15,606 July 2021 Mezzanine Loan — 280,000 34,124 — August 2022 Mezzanine Loan (12) — — — 15,369 Mortgage/ Mezzanine Loan (6) — — — 32,847 Mortgage/Mezzanine Loan (6) — — — 22,959 Mezzanine Loan (13) — — — 14,957 Mortgage/Mezzanine Loan (14) — — — 145,239 Total floating rate $ 181,320 $ 3,498,215 $ 1,243,925 $ 1,232,178 Total $ 181,320 $ 7,115,310 $ 1,876,759 $ 1,592,537 (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) These loans were purchased at par in April and May 2017 and were in maturity default at the time of acquisition. At the time the loans were purchased, the Company expected to collect all contractually required payments, including interest. In August 2017, the Company determined that it was probable that the loans would not be repaid in full and therefore, the loans were put on non-accrual status. No impairment was recorded as the Company believes that the fair value of the property exceeds the carrying amount of the loans. The loans had an outstanding balance including accrued interest of $259.3 million at the time that they were put on non-accrual status. (4) In September 2014, we acquired a $26.4 million mortgage loan at a $0.2 million discount and a $5.7 million junior mortgage participation at a $5.7 million discount. The junior mortgage participation was a nonperforming loan at acquisition, is currently on non-accrual status and has no carrying value. (5) 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) $1.2 million , (b) $12.0 million , (c) $14.6 million , (d) $14.1 million , (e) $5.1 million , and (f) $21.2 million (6) This loan was repaid in June 2017. (7) This loan was repaid in March 2017. (8) This loan was extended in October 2017. (9) This loan was extended in January 2017. (10) This loan was extended in September 2017. (11) $66.1 million of outstanding principal was syndicated in February 2017. (12) This loan was repaid in September 2017. (13) This loan was contributed to a joint venture in May 2017. (14) This loan was repaid in January 2017. Preferred Equity Investments As of September 30, 2017 and December 31, 2016 , we held the following preferred equity investments with an aggregate weighted average current yield of 6.98% at September 30, 2017 (in thousands): Type September 30, 2017 September 30, 2017 September 30, 2017 (1) December 31, 2016 (1) Mandatory Redemption (2) Preferred Equity (3) $ — $ 272,000 $ 143,980 $ — April 2021 Preferred Equity (4) — — — 9,982 Preferred Equity (5) — — — 37,893 Total $ — $ 272,000 $ 143,980 $ 47,875 (1) Carrying value is net of deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options. (3) In February 2016, we closed on the sale of 885 Third Avenue and retained a preferred equity position in the property. The sale did not meet the criteria for sale accounting under the full accrual method in ASC 360-20, Property, Plant and Equipment - Real Estate Sales. As a result the property remained on our consolidated balance sheet until the criteria was met in April 2017 at which time the property was deconsolidated and the preferred equity investment was recognized. (4) This investment was redeemed in May 2017. (5) This investment was redeemed in April 2017. At September 30, 2017 and December 31, 2016 , all debt and preferred equity investments were performing in accordance with the terms of the relevant investments, with the exception of a mortgage and junior mortgage participation purchased in maturity default in May 2017 and April 2017 discussed in subnote 3 of the Debt Investments table above and a junior mortgage participation acquired in September 2014, which was acquired for zero and has a carrying value of zero , as further discussed in subnote 4 of the Debt Investments table above. We have determined that we have one portfolio segment of financing receivables at September 30, 2017 and 2016 comprising commercial real estate which is primarily recorded in debt and preferred equity investments. Included in other assets is an additional amount of financing receivables totaling $65.6 million and $99.5 million at September 30, 2017 and December 31, 2016 , respectively. No financing receivables were 90 days past due at September 30, 2017 .

Investments in Unconsolidated J

Investments in Unconsolidated Joint Ventures	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 , 800 Third Avenue, 21 East 66th Street, 605 West 42 nd Street, 333 East 22nd Street, One Vanderbilt, 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 $ 598.7 million as of September 30, 2017 . As of December 31, 2016 , 650 Fifth Avenue, 800 Third Avenue, 21 East 66th Street, 605 West 42 nd Street, 333 East 22nd Street, and certain properties within the Stonehenge Portfolio were VIEs in which we were not the primary beneficiary. Our net equity investment in these VIEs was $220.1 million as of December 31, 2016 . Our maximum loss is limited to the amount of our equity investment in these VIEs. 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 September 30, 2017 : Property Partner Ownership (1) Economic (1) Unaudited Approximate Square Feet Acquisition Date (2) Acquisition (2) (in thousands) 100 Park Avenue Prudential Real Estate Investors 49.90% 49.90% 834,000 February 2000 $ 95,800 717 Fifth Avenue Jeff Sutton/Private Investor 10.92% 10.92% 119,500 September 2006 251,900 800 Third Avenue Private Investors 60.52% 60.52% 526,000 December 2006 285,000 1745 Broadway Ivanhoe Cambridge, Inc. 56.87% 56.87% 674,000 April 2007 520,000 Jericho Plaza Onyx Equities/Credit Suisse 11.67% 11.67% 640,000 April 2007 210,000 11 West 34th Street Private Investor/ 30.00% 30.00% 17,150 December 2010 10,800 3 Columbus Circle (3) The Moinian Group 48.90% 48.90% 741,500 January 2011 500,000 280 Park Avenue Vornado Realty Trust 50.00% 50.00% 1,219,158 March 2011 400,000 1552-1560 Broadway (4) Jeff Sutton 50.00% 50.00% 57,718 August 2011 136,550 724 Fifth Avenue Jeff Sutton 50.00% 50.00% 65,010 January 2012 223,000 10 East 53rd Street Canadian Pension Plan Investment Board 55.00% 55.00% 354,300 February 2012 252,500 521 Fifth Avenue Plaza Global 50.50% 50.50% 460,000 November 2012 315,000 21 East 66th Street (5) Private Investors 32.28% 32.28% 13,069 December 2012 75,000 650 Fifth Avenue (6) Jeff Sutton 50.00% 50.00% 69,214 November 2013 — 121 Greene Street Jeff Sutton 50.00% 50.00% 7,131 September 2014 27,400 175-225 Third Street Brooklyn, New York KCLW 3rd Street LLC/LIVWRK LLC 95.00% 95.00% — October 2014 74,600 55 West 46th Street Prudential Real Estate Investors 25.00% 25.00% 347,000 November 2014 295,000 Stonehenge Portfolio (7) Various Various Various 1,439,016 February 2015 36,668 131-137 Spring Street Invesco Real Estate 20.00% 20.00% 68,342 August 2015 277,750 605 West 42nd Street The Moinian Group 20.00% 20.00% 927,358 April 2016 759,000 11 Madison Avenue PGIM Real Estate 60.00% 60.00% 2,314,000 August 2016 2,605,000 333 East 22nd Street (8) Private Investors 33.33% 33.33% 26,926 August 2016 — 400 E 57th Street (9) BlackRock, Inc and Stonehenge Partners 51.00% 41.00% 290,482 October 2016 170,000 One Vanderbilt (10) National Pension Service of Korea/Hines Interest LP 71.01% 71.01% — January 2017 3,310,000 Mezzanine Loan (11) Private Investors 33.33% 33.33% — May 2017 15,000 (1) Ownership interest and economic interest represent the Company's interests in the joint venture as of September 30, 2017 . Changes in ownership or economic interests, if any, within the current year are disclosed in the notes below. (2) Acquisition date and price represent the date on which the Company initially acquired an interest in the joint venture and the actual or implied gross purchase price for the joint venture on that date. Acquisition date and price are not adjusted for subsequent acquisitions or dispositions of interest. (3) As a result of the sale of a condominium interest in September 2012, Young & Rubicam, Inc., or Y&R, owns floors three through eight at the property. Because the joint venture has an option to repurchase these floors, the gain associated with this sale was deferred. (4) The purchase price represents only the purchase of the 1552 Broadway interest which comprised approximately 13,045 square feet. 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. (5) We hold a 32.28 % interest in three retail and two residential units at the property and a 16.14 % interest in three residential units at the property. (6) The joint venture owns a long-term leasehold interest in the retail space at 650 Fifth Avenue. In connection with the ground lease obligation, SLG provided a performance guaranty and our joint venture partner executed a contribution agreement to reflect its pro rata obligation. In the event the property is converted into a condominium unit and the landlord elects the purchase option, the joint venture shall be obligated to acquire the unit at the then fair value. (7) In March 2017, the Company sold a partial interest in the Stonehenge Portfolio as further described under Sale of Joint Venture Interest or Properties below. (8) The joint venture acquired a leasehold interest in the property in October 2016. (9) In October 2016, the Company sold a 49% interest in this property to an investment account managed by BlackRock, Inc. The Company's 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. The Company's joint venture with Stonehenge remains consolidated resulting in the combined 51% interest being shown within investments in unconsolidated joint ventures on the Company's balance sheet. (10) In January 2017, the Company admitted two partners, National Pension Service of Korea and Hines Interest LP, into the One Vanderbilt Avenue development project. In April 2017, the criteria for deconsolidation were met, and the development is shown within investments in unconsolidated joint ventures. The partners have committed aggregate equity to the project totaling no less than $525 million and their ownership interest in the joint venture is based on their capital contributions, up to an aggregate maximum of 29.0% . At September 30, 2017 the total of the two partners' ownership interests based on equity contributed was 3.49% . (11) In May 2017, the Company contributed a mezzanine loan secured by a commercial property in midtown Manhattan to a joint venture and retained a 33.33% interest in the venture. The carrying value is net of $10.0 million that was sold, which is 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. In October 2017, the initial maturity date of November 2017 was extended to November 2018. Acquisition, Development and Construction Arrangements Based on the characteristics of the following arrangements, which are similar to those of an investment, combined with the expected residual profit of not greater than 50% , we have accounted for these debt and preferred equity investments under the equity method. As of September 30, 2017 and December 31, 2016, the carrying value for acquisition, development and construction arrangements were as follows (in thousands): Loan Type September 30, 2017 December 31, 2016 Maturity Date Mezzanine Loan and Preferred Equity (1) $ 100,000 $ 100,000 March 2018 Mezzanine Loan (2) 44,881 45,622 February 2022 Mezzanine Loan (3) 25,854 24,542 July 2036 $ 170,735 $ 170,164 (1) These loans were extended in February 2017. (2) We have an option to convert our loan to an equity interest subject to certain conditions. We have determined that our option to convert the loan to equity is not a derivative financial instrument pursuant to GAAP. (3) The Company has the ability to convert this loan into an equity position starting in 2021 and the borrower is able to force this conversion in 2024. Sale of Joint Venture Interests or Properties The following table summarizes the investments in unconsolidated joint ventures sold during the nine months ended September 30, 2017 : Property Ownership Interest Disposition Date Type of Sale Gross Asset Valuation (in thousands) (1) Gain on Sale (in thousands) (2) Stonehenge Portfolio (partial) Various March 2017 Ownership Interest $ 300,000 $ 871 102 Greene Street 10.00% September 2017 Ownership Interest $ 43,500 $ 283 (1) Represents implied gross valuation for the joint venture or sales price of the property. (2) Represents the Company's share of the gain. In May 2017, our investment in a joint venture that owned two mezzanine notes secured by interests in the entity that owns 76 11th Avenue was repaid after the joint venture received repayment of the underlying loans. In May 2017, we recognized a gain of $13.0 million related to the sale in May 2014 of our ownership interest in 747 Madison Avenue. The sale did not meet the criteria for sale accounting at that time and, therefore, remained on our consolidated financial statements. The sale criteria was met in the second quarter of 2017 resulting in recognition of the deferred gain on the sale. Joint Venture Mortgages and Other Loans Payable We generally finance our joint ventures with non-recourse debt. In certain cases we have provided guarantees or master leases for tenant space, which terminate upon the satisfaction of specified circumstances or repayment of the underlying loans. The first mortgage notes and other loans payable collateralized by the respective joint venture properties and assignment of leases at September 30, 2017 and December 31, 2016 , respectively, are as follows (amounts in thousands): Property Economic (1) Maturity Date Interest Rate (2) September 30, 2017 December 31, 2016 Fixed Rate Debt: 521 Fifth Avenue 50.50 % November 2019 3.73 % $ 170,000 $ 170,000 717 Fifth Avenue (3) 10.92 % July 2022 4.45 % 300,000 300,000 Property Economic (1) Maturity Date Interest Rate (2) September 30, 2017 December 31, 2016 717 Fifth Avenue (3) 10.92 % July 2022 5.50 % 355,328 355,328 650 Fifth Avenue 50.00 % October 2022 4.95 % 225,000 — 21 East 66th Street 32.28 % April 2023 3.60 % 12,000 12,000 3 Columbus Circle 48.90 % March 2025 3.61 % 350,000 350,000 11 Madison Avenue 60.00 % September 2025 3.84 % 1,400,000 1,400,000 800 Third Avenue 60.52 % February 2026 3.37 % 177,000 177,000 400 East 57th Street 41.00 % November 2026 3.00 % 100,000 100,000 Stonehenge Portfolio (4) Various Various 4.17 % 359,095 362,518 1745 Broadway (5) — 340,000 Total fixed rate debt $ 3,448,423 $ 3,566,846 Floating Rate Debt: 55 West 46th Street (6) 25.00 % October 2017 3.52 % $ 165,328 $ 157,322 175-225 Third Street Brooklyn, New York 95.00 % December 2017 5.25 % 40,000 40,000 Jericho Plaza (7) 11.67 % March 2018 5.37 % 79,530 76,993 724 Fifth Avenue 50.00 % April 2018 3.64 % 275,000 275,000 1552 Broadway (8) 50.00 % April 2018 5.41 % 185,410 185,410 280 Park Avenue (9) 50.00 % September 2019 3.09 % 1,200,000 900,000 121 Greene Street 50.00 % November 2019 2.72 % 15,000 15,000 1745 Broadway (10) 56.87 % January 2020 3.07 % 345,000 — 10 East 53rd Street 55.00 % February 2020 3.47 % 170,000 125,000 131-137 Spring Street 20.00 % August 2020 2.77 % 141,000 141,000 11 West 34th Street 30.00 % January 2021 2.68 % 23,000 23,000 100 Park Avenue 49.90 % February 2021 2.97 % 360,000 360,000 One Vanderbilt (11) 71.01 % September 2021 4.72 % 271,229 — 605 West 42nd Street (12) 20.00 % August 2027 2.84 % 550,000 539,000 21 East 66th Street 32.28 % June 2033 3.62 % 1,667 1,726 Stonehenge Portfolio Various April 2018 2.47 % 55,340 65,577 650 Fifth Avenue (13) — 77,500 Total floating rate debt $ 3,877,504 $ 2,982,528 Total joint venture mortgages and other loans payable $ 7,325,927 $ 6,549,374 Deferred financing costs, net (127,318 ) (95,408 ) Total joint venture mortgages and other loans payable, net $ 7,198,609 $ 6,453,966 (1) Economic interest represent the Company's interests in the joint venture as of September 30, 2017 . Changes in ownership or economic interests, if any, within the current year are disclosed in the notes to the investment in unconsolidated joint ventures note above. (2) Effective weighted average interest rate for the three months ended September 30, 2017 , taking into account interest rate hedges in effect during the period. (3) These loans are comprised of a $300.0 million fixed rate mortgage loan and $355.3 million mezzanine loan. The mezzanine loan is subject to accretion based on the difference between contractual interest rate and contractual pay rate. (4) Amount is comprised of $34.0 million , $137.7 million , $172.5 million , and $14.9 million in fixed-rate mortgages that mature in November 2017, August 2019, June 2024, and February 2027, respectively. (5) In January 2017, this loan was refinanced with a floating rate loan as shown above. (6) This loan has a committed amount of $190.0 million , of which $24.7 million was unfunded as of September 30, 2017 . In October 2017, this loan was refinanced with a new $195.0 million mortgage loan with a floating interest rate of 213 basis points over 30-day LIBOR and a maturity date of November 2020. (7) The property secures a two year $100.0 million loan, of which $79.5 million is currently outstanding. (8) These loans are comprised of a $145.0 million mortgage loan and a $41.5 million mezzanine loan. As of September 30, 2017 , $0.6 million of the mortgage loan and $0.5 million of the mezzanine loan were unfunded. In October 2017, this loan was refinanced with a new $195.0 million mortgage loan with a floating interest rate of 265 basis points over 30-day LIBOR and a maturity date of October 2020. (9) In August 2017, this loan was refinanced with a new $1.075 billion mortgage loan and a new $125.0 million mezzanine loan, which carry floating interest rates of 148 basis points over 30-day LIBOR and 385 basis points over 30-day LIBOR, respectively. Both the mortgage loan and mezzanine loan initially mature in September 2019. (10) This loan has a committed amount of $375.0 million , of which $30.0 million was unfunded as of September 30, 2017 . (11) This loan is a $1.5 billion construction facility in connection with the development of One Vanderbilt. This facility bears interest at 350 basis points over 30-day LIBOR, with reduction based on meeting certain conditions, and has an initial five -year term with two one -year extension options. Advances under the loan are subject to incurred costs, funded equity, loan to value thresholds, and entering into construction contracts. (12) In August 2017, this loan was refinanced with a new $550.0 million mortgage note, with a floating interest rate of 144 basis points over 30-day LIBOR and a maturity date of August 2027. (13) In September 2017, this loan was refinanced with a fixed rate loan as shown above. We act as the operating partner and day-to-day manager for all our joint ventures, except for 800 Third Avenue, Jericho Plaza, 280 Park Avenue, 3 Columbus Circle, 21 East 66th Street, 175-225 Third Street, 605 West 42nd Street, 400 East 57th Street, and the Stonehenge Portfolio. We are entitled to receive fees for providing management, leasing, construction supervision and asset management services to certain of our joint ventures. We earned $2.9 million and $28.1 million from these services for the three and nine months ended September 30, 2017 , respectively. We earned $2.0 million and $4.5 million from these services for the three and nine months ended September 30, 2016 , respectively. 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 September 30, 2017 and December 31, 2016 are as follows (in thousands): September 30, 2017 December 31, 2016 Assets Commercial real estate property, net $ 9,944,280 $ 9,131,717 Cash and restricted cash 370,596 328,455 Tenant and other receivables, related party receivables, and deferred rents receivable, net of allowance 267,244 232,778 Debt and preferred equity investments, net 201,731 336,164 Other assets 636,365 683,481 Total assets $ 11,420,216 $ 10,712,595 Liabilities and members' equity Mortgages and other loans payable, net $ 7,198,609 $ 6,453,966 Deferred revenue/gain 340,310 356,414 Other liabilities 411,261 391,500 Members' equity 3,470,036 3,510,715 Total liabilities and members' equity $ 11,420,216 $ 10,712,595 Company's investments in unconsolidated joint ventures $ 2,045,796 $ 1,890,186 The combined statements of operations for the unconsolidated joint ventures, for the three and nine months ended September 30, 2017 and 2016 , are as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Total revenues $ 216,100 $ 184,221 $ 643,210 $ 498,308 Operating expenses 38,055 34,727 115,996 89,147 Ground rent 4,182 3,744 12,612 10,670 Real estate taxes 37,282 30,814 107,391 79,356 Interest expense, net of interest income 61,066 51,789 176,096 147,876 Amortization of deferred financing costs 4,030 7,155 17,994 17,667 Transaction related costs — 5,359 146 5,359 Depreciation and amortization 61,447 56,890 198,556 132,035 Total expenses 206,062 190,478 628,791 482,110 Loss on early extinguishment of debt (7,638 ) — (7,638 ) (1,606 ) Net income (loss) before gain on sale $ 2,400 $ (6,257 ) $ 6,781 $ 14,592 Company's equity in net income (loss) from unconsolidated joint ventures $ 4,078 $ (3,968 ) $ 14,104 $ 11,969

Deferred Costs

Deferred Costs	9 Months Ended
	Sep. 30, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred Costs	Deferred Costs Deferred costs at September 30, 2017 and December 31, 2016 consisted of the following (in thousands): September 30, 2017 December 31, 2016 Deferred leasing costs $ 464,788 $ 468,971 Less: accumulated amortization (216,807 ) (201,371 ) Deferred costs, net $ 247,981 $ 267,600

Mortgages and Other Loans Payab

Mortgages and Other Loans Payable	9 Months Ended
	Sep. 30, 2017
Mortgages and Other Loans Payable
Mortgages and Other Loans Payable	Mortgages and Other Loans Payable The first mortgages and other loans payable collateralized by the respective properties and assignment of leases or debt investments at September 30, 2017 and December 31, 2016 , respectively, were as follows (amounts in thousands): Property Maturity Date Interest Rate (1) September 30, 2017 December 31, 2016 Fixed Rate Debt: Unsecured Loan June 2018 4.81 % $ 16,000 $ 16,000 One Madison Avenue May 2020 5.91 % 494,264 517,806 762 Madison Avenue February 2022 5.00 % 771 7,694 100 Church Street July 2022 4.68 % 218,237 221,446 919 Third Avenue (2) June 2023 5.12 % 500,000 500,000 420 Lexington Avenue October 2024 3.99 % 300,000 300,000 1515 Broadway March 2025 3.93 % 876,613 888,531 400 East 58th Street (3) November 2026 3.00 % 40,000 40,000 Landmark Square January 2027 4.90 % 100,000 100,000 485 Lexington Avenue February 2027 4.25 % 450,000 450,000 1080 Amsterdam (4) February 2027 3.58 % 36,363 — 315 West 33rd Street February 2027 4.17 % 250,000 — Series J Preferred Units (5) April 2051 3.75 % 4,000 4,000 885 Third Avenue (6) — 267,650 FHLBNY Facility (7) — 105,000 FHLBNY Facility (7) — 100,000 Total fixed rate debt $ 3,286,248 $ 3,518,127 Floating Rate Debt: 719 Seventh Avenue February 2018 4.27 % $ 41,171 $ 37,388 183, 187 Broadway & 5-7 Dey Street May 2018 3.92 % 58,000 58,000 2016 Master Repurchase Agreement July 2018 3.73 % 184,642 184,642 220 East 42nd Street October 2020 2.82 % 275,000 275,000 One Vanderbilt Avenue (8) — 64,030 1080 Amsterdam (9) — 3,525 Total floating rate debt $ 558,813 $ 622,585 Total fixed rate and floating rate debt $ 3,845,061 $ 4,140,712 Mortgages reclassed to liabilities related to assets held for sale — — Total mortgages and other loans payable $ 3,845,061 $ 4,140,712 Deferred financing costs, net of amortization (40,887 ) (66,882 ) Total mortgages and other loans payable, net $ 3,804,174 $ 4,073,830 (1) Effective weighted average interest rate for the quarter ended September 30, 2017 , taking into account interest rate hedges in effect during the period. (2) We own a 51.0% controlling interest in the consolidated joint venture that is the borrower on this loan. (3) The loan carries a fixed interest rate of 3.00% for the first 5 years and is prepayable without penalty in year 5 . (4) The loan is comprised of a $35.5 million mortgage loan and $0.9 million subordinate loan with a fixed interest rate of 3.50% and 7.00% , respectively, for the first 5 years and is prepayable without penalty in year 5 . (5) In connection with the acquisition of a commercial real estate property, the Operating Partnership issued $4.0 million , 3.75% Series J Preferred Units of limited partnership interest, or the Series J Preferred Units, with a mandatory liquidation preference of $1,000 per unit. The Series J Preferred Units are accounted for as debt because they can be redeemed in cash by the Operating Partnership on the earlier of (i) the date of the sale of the property or (ii) April 30, 2051 or at the option of the unitholders as provided for in the related agreement. (6) In February 2016, we closed on the sale of 885 Third Avenue. The sale did not meet the criteria for sale accounting at that time. In April 2017, the mortgage was refinanced by the buyer, resulting in the Company deconsolidating the property from its financial statements in the second quarter of 2017. (7) The facility was repaid in January 2017. (8) In September 2016, we closed on a $1.5 billion construction facility in connection with the development of One Vanderbilt Avenue. In January 2017, we admitted two partners, National Pension Service of Korea and Hines Interest LP, into the One Vanderbilt Avenue development project. In April 2017, the criteria for deconsolidation were met, and the development is shown within investments in unconsolidated joint ventures. See Note 6, "Investments in Unconsolidated Joint Ventures". (9) In January 2017, this loan was refinanced with a fixed rate loan as shown above. At September 30, 2017 and December 31, 2016 , the gross book value of the properties and debt and preferred equity investments collateralizing the mortgages and other loans payable, not including assets held for sale, was approximately $6.7 billion and $6.0 billion , respectively. Federal Home Loan Bank of New York Facility The Company’s wholly-owned subsidiary, Belmont Insurance Company, or Belmont, a New York licensed captive insurance company, was a member of the Federal Home Loan Bank of New York, or FHLBNY. In January 2017, all funds borrowed from the FHLBNY were repaid and Belmont's membership was terminated in February 2017. Master Repurchase Agreements The Company has entered into two Master Repurchase Agreements, or MRAs, known as the 2016 MRA and 2017 MRA, which provide us with the ability to sell certain debt 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 facilities 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 recollateralize 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 through the 2012 credit facility, as defined below. In June 2017, we entered into the 2017 MRA, with a maximum facility capacity of $300.0 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 has an initial one year term, with two one year extension options. At September 30, 2017 , the facility had a carrying value of $(1.1) million , representing deferred financing costs presented within other liabilities. In July 2016, we entered into a restated 2016 MRA, with a maximum facility capacity of $300.0 million. The facility bears interest ranging from 225 and 400 basis points over 30-day LIBOR depending on the pledged collateral and has an initial two -year term, with a one year extension option. Since December 6, 2015, we have been required to pay monthly in arrears a 25 basis point fee on the excess of $150.0 million over the average daily balance during the period when the average daily balance is less than $150.0 million . At September 30, 2017 , the facility had a carrying value of $182.8 million , net of deferred financing costs.

Corporate Indebtedness

Corporate Indebtedness	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Corporate Indebtedness	Corporate Indebtedness 2012 Credit Facility In August 2016, we entered into an amendment to the credit facility that was originally entered into by the Company in November 2012, referred to as the 2012 credit facility. As of September 30, 2017 , the 2012 credit facility, as amended, consisted of a $1.6 billion revolving credit facility and a $1.2 billion term loan, with a maturity date of March 29, 2019 and June 30, 2019, respectively. The revolving credit facility has an as-of-right extension to March 29, 2020. We also have an option, subject to customary conditions, to increase the capacity under the revolving credit facility to $3.0 billion at any time prior to the maturity date for the revolving credit facility without the consent of existing lenders, by obtaining additional commitments from our existing lenders and other financial institutions. As of September 30, 2017 , the 2012 credit facility bore interest at a spread over LIBOR ranging from (i) 87.5 basis points to 155 basis points for loans under the revolving credit facility and (ii) 95 basis points to 190 basis points for loans under the term loan facility, in each case based on the credit rating assigned to the senior unsecured long term indebtedness of ROP. At September 30, 2017 , the applicable spread was 125 basis points for the revolving credit facility and 140 basis points for the term loan facility. At September 30, 2017 , the effective interest rate, including the effect of interest rate swaps, was 2.49% for the revolving credit facility and 2.49% for the term loan facility. 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 ROP. As of September 30, 2017 , the facility fee was 25 basis points. As of September 30, 2017 , we had $80.8 million of outstanding letters of credit, $280.0 million drawn under the revolving credit facility and $1.2 billion outstanding under the term loan facility, with total undrawn capacity of $1.2 billion under the 2012 credit facility. At September 30, 2017 and December 31, 2016 , the revolving credit facility had a carrying value of $275.8 million and $(6.3) million , respectively, net of deferred financing costs. The December 31, 2016 carrying value represents deferred financing costs and is presented within other liabilities. At September 30, 2017 and December 31, 2016 , the term loan facility had a carrying value of $1.2 billion and $1.2 billion , respectively, net of deferred financing costs. The Company, the Operating Partnership and ROP are all borrowers jointly and severally obligated under the 2012 credit facility. None of our other subsidiaries are obligors under the 2012 credit facility. The 2012 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 September 30, 2017 and December 31, 2016 , respectively, by scheduled maturity date (dollars in thousands): Issuance September 30, September 30, December 31, Coupon Rate (1) Effective Rate Initial Term (in Years) Maturity Date October 12, 2010 (2) $ 269,000 $ 268,628 $ 334,077 3.00 % 3.00 % 7 October 2017 August 5, 2011 (3) 250,000 249,934 249,880 5.00 % 5.00 % 7 August 2018 March 16, 2010 (3) 250,000 250,000 250,000 7.75 % 7.75 % 10 March 2020 November 15, 2012 (3) 200,000 200,000 200,000 4.50 % 4.50 % 10 December 2022 December 17, 2015 (3) 100,000 100,000 100,000 4.27 % 4.27 % 10 December 2025 $ 1,069,000 $ 1,068,562 $ 1,133,957 Deferred financing costs, net (4,018 ) (5,642 ) $ 1,069,000 $ 1,064,544 $ 1,128,315 (1) Interest on the senior unsecured notes is payable semi-annually with principal and unpaid interest due on the scheduled maturity dates. (2) Issued by the Operating Partnership. The notes were senior unsecured obligations of the Operating Partnership and exchangeable at a calculated exchange rate upon the occurrence of specified events and during the period beginning on the twenty-second scheduled trading day prior to the maturity date and ending on the second business day prior to the maturity date, into cash, or a combination of cash and shares of SL Green's common stock, if any, at our option. In accordance with the terms of the indenture, the notes became exchangeable commencing September 14, 2017 and the Operating Partnership elected to settle exchanges in cash. In October 2017, all note holders elected to exchange the notes and the notes were repaid for $350.8 million , excluding accrued interest based on the applicable exchange rate. (3) Issued by the Company, the Operating Partnership and ROP, as co-obligors. In October 2017, the Company, the Operating Partnership and ROP, as co-obligors issued an additional $100.0 million of the 4.50% senior unsecured bonds due December 2022. The additional notes priced at 105.334% plus accrued interest from June 1, 2017, with a yield to maturity of 3.298% . In October 2017, the Company issued $500.0 million of senior unsecured notes which will mature in October 2022 and bear interest at a fixed rate of 3.25% . Restrictive Covenants The terms of the 2012 credit facility, as amended, 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 September 30, 2017 and 2016 , 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. The effective weighted average interest rate for the quarter ended September 30, 2017 was 2.52% . 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, 2012 credit facility, trust preferred securities, senior unsecured notes and our share of joint venture debt as of September 30, 2017 , including as-of-right extension options and put options, were as follows (in thousands): Scheduled Amortization Principal Revolving Credit Facility Unsecured Term Loan Trust Preferred Securities Senior Unsecured Notes Total Joint Venture Debt Remaining 2017 $ 12,846 $ — $ — $ — $ — $ 269,000 (1) $ 281,846 $ 79,787 2018 54,937 299,813 — — — 250,000 604,750 242,799 2019 59,618 — — 1,183,000 — — 1,242,618 705,574 2020 41,427 679,531 280,000 — — 250,000 1,250,958 320,914 2021 30,418 — — — — — 30,418 376,765 Thereafter 90,532 2,575,939 — — 100,000 300,000 3,066,471 1,465,371 $ 289,778 $ 3,555,283 $ 280,000 $ 1,183,000 $ 100,000 $ 1,069,000 $ 6,477,061 $ 3,191,210 (1) The $269.0 million of 3.00% convertible notes which matured in October 2017 became exchangeable commencing September 14, 2017 and the Operating Partnership elected to settle exchanges in cash. In October 2017, all note holders elected to exchange the notes and the notes were repaid for $350.8 million . Consolidated interest expense, excluding capitalized interest, was comprised of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Interest expense before capitalized interest $ 72,859 $ 78,715 $ 217,273 $ 276,437 Interest capitalized (6,869 ) (6,084 ) (19,892 ) (18,135 ) Interest income (356 ) (66 ) (1,269 ) (1,976 ) Interest expense, net $ 65,634 $ 72,565 $ 196,112 $ 256,326

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2017
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, the chairman of SL Green's 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 profit participation, which is included in other income on the consolidated statements of operations, was $1.0 million and $3.0 million for the three and nine months ended September 30, 2017 , respectively, and was $0.8 million and $2.6 million for the three and nine months ended September 30, 2016 , respectively. We also recorded expenses for these services, inclusive of capitalized expenses, of $5.7 million and $16.0 million for the three and nine months ended September 30, 2017 , respectively, for these services (excluding services provided directly to tenants), and $5.3 million and $16.1 million for the three and nine months ended September 30, 2016 , respectively. 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 $0.4 million for the three and nine months ended September 30, 2017 , respectively, and $0.1 million and $0.3 million for the three and nine months ended September 30, 2016 , respectively. One Vanderbilt Investment In December 2016, we entered into agreements with entities owned and controlled by Marc Holliday and 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. Fifty percent of these interests were purchased on December 31, 2016 and the remaining fifty percent will be purchased on December 31, 2017. The entities owned and controlled by Messrs. Holliday and Mathias will pay $1.4 million and $1.0 million , respectively, which equals 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. 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 Investments in Unconsolidated Joint Ventures. Amounts due from joint ventures and related parties at September 30, 2017 and December 31, 2016 consisted of the following (in thousands): September 30, 2017 December 31, 2016 Due from joint ventures $ 16,736 $ 1,240 Other 7,332 14,616 Related party receivables $ 24,068 $ 15,856

Noncontrolling Interests on the

Noncontrolling Interests on the Company's Consolidated Financial Statements	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 and December 31, 2016 , the noncontrolling interest unit holders owned 4.45% , or 4,541,765 units, and 4.16% , or 4,363,716 units, of the Operating Partnership, respectively. As of September 30, 2017 , 4,541,765 shares of SL Green's 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 SL Green's common stock at the end of the reporting period. Below is the rollforward analysis of the activity relating to the noncontrolling interests in the Operating Partnership as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Balance at beginning of period $ 473,882 $ 424,206 Distributions (10,639 ) (12,671 ) Issuance of common units 23,273 78,495 Redemption of common units (15,353 ) (31,805 ) Net income 2,707 10,136 Accumulated other comprehensive income allocation (303 ) 1,299 Fair value adjustment (2,669 ) 4,222 Balance at end of period $ 470,898 $ 473,882 Preferred Units of Limited Partnership Interest in the Operating Partnership The Operating Partnership has 1,902,000 4.50% Series G Preferred Units of limited partnership interest, or the Series G Preferred Units outstanding, with a liquidation preference of $25.00 per unit, which were issued in January 2012 in conjunction with an acquisition. The Series G Preferred unitholders receive annual dividends of $1.125 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series G Preferred 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) $88.50 . The common units of limited partnership interest in the Operating Partnership may be redeemed in exchange for SL Green's 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. The Operating Partnership has 60 Series F Preferred Units outstanding with a mandatory liquidation preference of $1,000.00 per unit. The Operating Partnership has authorized up to 700,000 3.50% Series K Preferred Units of limited partnership interest, or the Series K Preferred Units, with a liquidation preference of $25.00 per unit. In August 2014, the Company issued 563,954 Series K Preferred Units in conjunction with an acquisition. The Series K Preferred unitholders receive annual dividends of $0.875 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series K Preferred Units can be redeemed at any time, at the option of the unitholder, either for cash or 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) $134.67 . The Operating Partnership has authorized up to 500,000 4.00% Series L Preferred Units of limited partnership interest, or the Series L Preferred Units, with a liquidation preference of $25.00 per unit. In August 2014, the Company issued 378,634 Series L Preferred Units in conjunction with an acquisition. The Series L Preferred unitholders receive annual dividends of $1.00 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series L Preferred Units can be redeemed at any time at par for cash at the option of the unitholder. The Operating Partnership has authorized up to 1,600,000 3.75% Series M Preferred Units of limited partnership interest, or the Series M Preferred Units, with a liquidation preference of $25.00 per unit. In February 2015, the Company issued 1,600,000 Series M Preferred Units in conjunction with the acquisition of ownership interests in and relating to certain residential and retail real estate properties. The Series M Preferred unitholders receive annual dividends of $0.9375 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series M Preferred Units can be redeemed at any time at par for cash at the option of the unitholder. The Operating Partnership has authorized up to 552,303 3.00% Series N Preferred Units of limited partnership interest, or the Series N Preferred Units, with a liquidation preference of $25.00 per unit. In June 2015, the Company issued 552,303 Series N Preferred Units in conjunction with an acquisition. The Series N Preferred unitholders receive annual dividends of $0.75 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series N Preferred Units can be redeemed at any time at par for cash at the option of the unitholder. The Operating Partnership has authorized an aggregate of one 6.25% Series O Preferred Unit of limited partnership interest, or the Series O Preferred Unit. In June 2015, the Company issued the Series O Preferred Unit in connection with an acquisition. The Operating Partnership has authorized up to 200,000 4.00% Series P Preferred Units of limited partnership interest, or the Series P Preferred Units, with a liquidation preference of $25.00 per unit. In July 2015, the Company issued 200,000 Series P Preferred Units in conjunction with an acquisition. The Series P Preferred unitholders receive annual dividends of $1.00 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series P Preferred Units can be redeemed at any time at par for cash at the option of the unitholder. The Operating Partnership has authorized up to 268,000 3.50% Series Q Preferred Units of limited partnership interest, or the Series Q Preferred Units, with a liquidation preference of $25.00 per unit. In July 2015, the Company issued 268,000 Series Q Preferred Units in conjunction with an acquisition. The Series Q Preferred unitholders receive annual dividends of $0.875 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series Q Preferred Units can be redeemed at any time, at the option of the unitholder, either for cash or 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) $148.95 . The Operating Partnership has authorized up to 400,000 3.50% Series R Preferred Units of limited partnership interest, or the Series R Preferred Units, with a liquidation preference of $25.00 per unit. In August 2015, the Company issued 400,000 Series R Preferred Units in conjunction with an acquisition. The Series R Preferred unitholders receive annual dividends of $0.875 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series R Preferred Units can be redeemed at any time, at the option of the unitholder, either for cash or 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) $154.89 . The Operating Partnership has authorized up to 1,077,280 4.00% Series S Preferred Units of limited partnership interest, or the Series S Preferred Units, with a liquidation preference of $25.00 per unit. In August 2015, the Company issued 1,077,280 Series S Preferred Units in conjunction with an acquisition. The Series S Preferred unitholders receive annual dividends of $1.00 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series S Preferred Units can be redeemed at any time at par for cash at the option of the unitholder. The Operating Partnership has authorized up to 230,000 2.75% Series T Preferred Units of limited partnership interest, or the Series T Preferred Units, with a liquidation preference of $25.00 per unit. In March 2016, the Company issued 230,000 Series T Preferred Units in conjunction with an acquisition. The Series T Preferred unitholders receive annual dividends of $0.6875 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Series T Preferred Units can be redeemed at any time at par, at the option of the unitholder, either for cash or 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) $119.02 . The Operating Partnership has authorized up to 680,000 4.50% Series U Preferred Units of limited partnership interest, or the Series U Preferred Units, with a liquidation preference of $25.00 per unit. In March 2016, the Company issued 680,000 Series U Preferred Units in conjunction with an acquisition. The Series U Preferred unitholders initially receive annual dividends of $1.125 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The annual dividend is subject to reduction upon the occurence of certain circumstances set forth in the terms of the Series U Preferred Units. The minimum annual dividend is $0.75 per unit. The Series U Preferred Units can be redeemed at any time at par for cash at the option of the unitholder. T hrough a consolidated subsidiary, we have authorized up to 109,161 3.50% Series A Preferred Units of limited partnership interest, or the Subsidiary Series A Preferred Units, with a liquidation preference of $1,000.00 per unit. In August 2015, the Company issued 109,161 Subsidiary Series A Preferred Units in conjunction with an acquisition. The Subsidiary Series A Preferred unitholders receive annual dividends of $35.00 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Subsidiary Series A Preferred Units can be redeemed at any time, at the option of the unitholder, either for cash or 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 September 30, 2017 , no Subsidiary Series B Preferred Units have been issued. Below is the rollforward analysis of the activity relating to the preferred units in the Operating Partnership as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Balance at beginning of period $ 302,010 $ 282,516 Issuance of preferred units — 22,793 Redemption of preferred units (125 ) (3,299 ) Balance at end of period $ 301,885 $ 302,010

Stockholders' Equity of the Com

Stockholders' Equity of the Company	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 , 97,445,509 shares of common stock and no shares of excess stock were issued and outstanding. In August 2016, our board of directors approved a stock repurchase plan under which we can buy up to $1.0 billion of shares of our common stock. At September 30, 2017 , repurchases made under the stock repurchase plans were as follows: Period Total number of shares purchased Average price paid per share Total number of shares purchased as part of the repurchase plan or programs Maximum approximate dollar value of shares that may yet be purchased under the plan (in millions) First quarter 2017 982 $103.89 982 $999.9 Second quarter 2017 2,447,153 $103.41 2,448,135 $746.8 Third quarter 2017 951,866 $101.67 3,400,001 $650.0 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 par for cash at our option. 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 In February 2015, 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 SL Green's common stock under the DRSPP. The DRSPP commenced on September 24, 2001. Earnings per Share SL Green's earnings per share for the three and nine months ended September 30, 2017 and 2016 are computed as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Numerator 2017 2016 2017 2016 Basic Earnings: Income attributable to SL Green common stockholders $ 38,869 $ 34,252 $ 58,442 $ 190,930 Effect of Dilutive Securities: Redemption of units to common shares 1,812 1,663 2,707 8,171 Diluted Earnings: Income attributable to SL Green common stockholders $ 40,681 $ 35,915 $ 61,149 $ 199,101 Three Months Ended September 30, Nine Months Ended September 30, Denominator 2017 2016 2017 2016 Basic Shares: Weighted average common stock outstanding 97,783 100,233 99,431 100,140 Effect of Dilutive Securities: Operating Partnership units redeemable for common shares 4,543 4,497 4,570 4,272 Stock-based compensation plans 244 413 279 349 Diluted weighted average common stock outstanding 102,570 105,143 104,280 104,761 SL Green has excluded 1,175,708 and 1,076,695 common stock equivalents from the diluted shares outstanding for the three and nine months ended September 30, 2017 , respectively, as they were anti-dilutive. SL Green has excluded 673,298 and 753,344 common stock equivalents from the diluted shares outstanding for the three and nine months ended September 30, 2016 , respectively, as they were anti-dilutive.

Partners' Capital of the Operat

Partners' Capital of the Operating Partnership	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 , 97,445,509 shares of common stock and no shares of excess stock were issued and outstanding. In August 2016, our board of directors approved a stock repurchase plan under which we can buy up to $1.0 billion of shares of our common stock. At September 30, 2017 , repurchases made under the stock repurchase plans were as follows: Period Total number of shares purchased Average price paid per share Total number of shares purchased as part of the repurchase plan or programs Maximum approximate dollar value of shares that may yet be purchased under the plan (in millions) First quarter 2017 982 $103.89 982 $999.9 Second quarter 2017 2,447,153 $103.41 2,448,135 $746.8 Third quarter 2017 951,866 $101.67 3,400,001 $650.0 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 par for cash at our option. 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 In February 2015, 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 SL Green's common stock under the DRSPP. The DRSPP commenced on September 24, 2001. Earnings per Share SL Green's earnings per share for the three and nine months ended September 30, 2017 and 2016 are computed as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Numerator 2017 2016 2017 2016 Basic Earnings: Income attributable to SL Green common stockholders $ 38,869 $ 34,252 $ 58,442 $ 190,930 Effect of Dilutive Securities: Redemption of units to common shares 1,812 1,663 2,707 8,171 Diluted Earnings: Income attributable to SL Green common stockholders $ 40,681 $ 35,915 $ 61,149 $ 199,101 Three Months Ended September 30, Nine Months Ended September 30, Denominator 2017 2016 2017 2016 Basic Shares: Weighted average common stock outstanding 97,783 100,233 99,431 100,140 Effect of Dilutive Securities: Operating Partnership units redeemable for common shares 4,543 4,497 4,570 4,272 Stock-based compensation plans 244 413 279 349 Diluted weighted average common stock outstanding 102,570 105,143 104,280 104,761 SL Green has excluded 1,175,708 and 1,076,695 common stock equivalents from the diluted shares outstanding for the three and nine months ended September 30, 2017 , respectively, as they were anti-dilutive. SL Green has excluded 673,298 and 753,344 common stock equivalents from the diluted shares outstanding for the three and nine months ended September 30, 2016 , respectively, as they were anti-dilutive.
SL Green Operating Partnership
Stockholders' Equity
Partners' Capital of the Operating Partnership	Partners' Capital of the Operating Partnership The Company is the sole general partner of the Operating Partnership and at September 30, 2017 owned 97,445,509 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. Limited Partner Units As of September 30, 2017 , limited partners other than SL Green owned 4.45% , or 4,541,765 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 and nine months ended September 30, 2017 and 2016, respectively are computed as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Numerator 2017 2016 2017 2016 Basic and Diluted Earnings: Net income attributable to SLGOP common unitholders $ 40,681 $ 35,915 $ 61,149 $ 199,101 Three Months Ended September 30, Nine Months Ended September 30, Denominator 2017 2016 2017 2016 Basic units: Weighted average common units outstanding 102,326 104,730 104,001 104,412 Effect of Dilutive Securities: Stock-based compensation plans 244 413 279 349 Diluted weighted average common units outstanding 102,570 105,143 104,280 104,761 The Operating Partnership has excluded 1,175,708 and 1,076,695 common unit equivalents from the diluted units outstanding for the three and nine months ended September 30, 2017 , respectively, as they were anti-dilutive. The Operating Partnership has excluded 673,298 and 753,344 common unit equivalents from the diluted units outstanding for the three and nine months ended September 30, 2016 , respectively, as they were anti-dilutive.

Share-based Compensation

Share-based Compensation	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based Compensation	Share-based Compensation We have stock-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. Fourth Amended and Restated 2005 Stock Option and Incentive Plan 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) granted after the effective date of the Fourth Amendment 2005 Plan 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., ten -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 SL Green's 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 September 30, 2017 , 8.7 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, including, among others, outstanding LTIP Units issued under our 2014 Outperformance Plan. Options are granted under the plan 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 or ten years from the date of grant, are not transferable other than on death, and generally vest in one 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 with the following weighted average assumptions for grants during the nine months ended September 30, 2017 and the year ended December 31, 2016 . September 30, 2017 December 31, 2016 Dividend yield 2.50 % 2.37 % Expected life 4.4 years 3.7 years Risk-free interest rate 1.73 % 1.57 % Expected stock price volatility 28.21 % 26.76 % A summary of the status of the Company's stock options as of September 30, 2017 and December 31, 2016 , and changes during the nine months ended September 30, 2017 and year ended December 31, 2016 are as follows: September 30, 2017 December 31, 2016 Options Outstanding Weighted Average Exercise Price Options Outstanding Weighted Average Exercise Price Balance at beginning of period $ 1,737,213 $ 98.44 $ 1,595,007 $ 95.52 Granted 171,000 105.70 445,100 105.86 Exercised (146,277 ) 84.02 (192,875 ) 76.90 Lapsed or cancelled (65,300 ) 122.30 (110,019 ) 123.86 Balance at end of period $ 1,696,636 $ 99.50 $ 1,737,213 $ 98.44 Options exercisable at end of period 939,485 $ 91.71 748,617 $ 87.72 Weighted average fair value of options granted during the period $ 3,775,639 $ 8,363,036 All options were granted with strike prices ranging from $20.67 to $128.82 . The remaining weighted average contractual life of the options outstanding was 3.6 years and the remaining average contractual life of the options exercisable was 2.8 years. During the three and nine months ended September 30, 2017 , we recognized compensation expense for these options of $2.0 million and $5.9 million , respectively. During the three and nine months ended September 30, 2016 , we recognized compensation expense for these options of $2.5 million and $6.4 million , respectively. As of September 30, 2017 , there was $10.6 million of total unrecognized compensation cost related to unvested stock options, which is expected to be recognized over a weighted average period of 1.7 years. Stock-based Compensation Effective January 1, 1999, the Company implemented a deferred compensation plan, or the Deferred Plan, where shares issued under the Deferred Plan were granted to certain employees, including certain of our executives and vesting will occur 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 September 30, 2017 and December 31, 2016 and charges during the nine months ended September 30, 2017 and the year ended December 31, 2016 , are as follows: September 30, 2017 December 31, 2016 Balance at beginning of period 3,202,031 3,137,881 Granted 300 98,800 Cancelled — (34,650 ) Balance at end of period 3,202,331 3,202,031 Vested during the period 86,736 83,822 Compensation expense recorded $ 7,277,054 $ 7,153,966 Weighted average fair value of restricted stock granted during the period $ 30,813 $ 10,650,077 The fair value of restricted stock that vested during the nine months ended September 30, 2017 and the year ended December 31, 2016 was $8.4 million and $7.6 million , respectively. As of September 30, 2017 there was $13.7 million of total unrecognized compensation cost related to restricted stock, which is expected to be recognized over a weighted average period of 1.7 years . For the three and nine months ended September 30, 2017 , $1.4 million and $5.0 million , respectively, was capitalized to assets associated with compensation expense related to our long-term compensation plans, restricted stock and stock options. For the three and nine months ended September 30, 2016 , $1.5 million and $4.4 million , respectively, was capitalized to assets associated with compensation expense related to our long-term compensation plans, restricted stock and stock options. We have granted LTIP Units, which include bonus, time-based and performance based awards, with a fair value of $20.5 million and $34.9 million as of September 30, 2017 and December 31, 2016 , 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 SL Green's 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 September 30, 2017 , there was $7.1 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 1.2 years . During the three and nine months ended September 30, 2017 , we recorded compensation expense related to bonus, time-based and performance based awards of $2.5 million and $15.1 million , respectively. During the three and nine months ended September 30, 2016 , we recorded compensation expense related to bonus, time-based and performance based awards of $2.3 million and $15.1 million , respectively. 2014 Outperformance Plan In August 2014, the compensation committee of the Company's board of directors approved the general terms of the SL Green Realty Corp. 2014 Outperformance Plan, or the 2014 Outperformance Plan. Participants in the 2014 Outperformance Plan may earn, in the aggregate, up to 610,000 LTIP Units in our Operating Partnership based on our total return to stockholders for the three -year period beginning September 1, 2014. Under the 2014 Outperformance Plan, two-thirds of the LTIP Units may be earned based on the Company’s absolute total return to stockholders and one-third of the LTIP Units may be earned based on relative total return to stockholders compared to the constituents of the MSCI REIT Index. Awards earned based on absolute total return to stockholders will be determined independently of awards earned based on relative total return to stockholders. In the event the Company’s performance reaches either threshold before the end of the three -year performance period, a pro-rata portion of the maximum award may be earned. For each component, if the Company’s performance reaches the maximum threshold beginning with the 19th month of the performance period, participants will earn one-third of the maximum award that may be earned for that component. If the Company’s performance reaches the maximum threshold during the third year of the performance period for a component, participants will earn two-thirds (or an additional one-third) of the maximum award that may be earned for that component. LTIP Units earned under the 2014 Outperformance Plan will be subject to continued vesting requirements, with 50% of any awards earned vesting on August 31, 2017 and the remaining 50% vesting on August 31, 2018, subject to continued employment with us through such dates. Participants will not be entitled to distributions with respect to LTIP Units granted under the 2014 Outperformance Plan unless and until they are earned. If LTIP Units are earned, each participant will also be entitled to the distributions that would have been paid had the number of earned LTIP Units been issued at the beginning of the performance period, with such distributions being paid in the form of cash or additional LTIP Units. Thereafter, distributions will be paid currently with respect to all earned LTIP Units, whether vested or unvested. The cost of the 2014 Outperformance Plan ( $29.2 million , subject to forfeitures), based on the portion of the 2014 Outperformance Plan granted as of September 30, 2017 , will be amortized into earnings through the final vesting period. We recorded compensation expense of $1.9 million and $8.2 million for the three and nine months ended September 30, 2017 , respectively, related to the 2014 Outperformance Plan. We recorded compensation expense of $1.8 million and $6.6 million for the three and nine months ended September 30, 2016 , respectively, related to the 2014 Outperformance Plan. 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 SL Green's 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 nine months ended September 30, 2017 , 11,510 phantom stock units and 9,171 shares of common stock were issued to our board of directors. We recorded compensation expense of $0.1 million and $2.2 million during the three and nine months ended September 30, 2017 , respectively, related to the Deferred Compensation Plan. We recorded compensation expense of $0.1 million and $1.9 million during the three and nine months ended September 30, 2016 , respectively, related to the Deferred Compensation Plan. As of September 30, 2017 , there were 98,637 phantom stock units outstanding pursuant to our Non-Employee Director's Deferral Program. Employee Stock Purchase Plan In 2007, the Company's board of directors adopted the 2008 Employee Stock Purchase Plan, or ESPP, to encourage our employees to increase their efforts to make our business more successful by providing equity-based incentives to eligible employees. The ESPP is intended to qualify as an "employee stock purchase plan" under Section 423 of the Code, and has been adopted by the board to enable our eligible employees to purchase the Company's shares of common stock through payroll deductions. The ESPP became effective on January 1, 2008 with a maximum of 500,000 shares of the common stock available for issuance, subject to adjustment upon a merger, reorganization, stock split or other similar corporate change. The Company filed a registration statement on Form S-8 with the SEC with respect to the ESPP. The common stock is offered for purchase through a series of successive offering periods. Each offering period will be three months in duration and will begin on the first day of each calendar quarter, with the first offering period having commenced on January 1, 2008. The ESPP provides for eligible employees to purchase the common stock at a purchase price equal to 85% of the lesser of (1) the market value of the common stock on the first day of the offering period or (2) the market value of the common stock on the last day of the offering period. The ESPP was approved by our stockholders at our 2008 annual meeting of stockholders. As of September 30, 2017 , 101,882 shares of SL Green's common stock had been issued under the ESPP.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income	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 September 30, 2017 , 97,445,509 shares of common stock and no shares of excess stock were issued and outstanding. In August 2016, our board of directors approved a stock repurchase plan under which we can buy up to $1.0 billion of shares of our common stock. At September 30, 2017 , repurchases made under the stock repurchase plans were as follows: Period Total number of shares purchased Average price paid per share Total number of shares purchased as part of the repurchase plan or programs Maximum approximate dollar value of shares that may yet be purchased under the plan (in millions) First quarter 2017 982 $103.89 982 $999.9 Second quarter 2017 2,447,153 $103.41 2,448,135 $746.8 Third quarter 2017 951,866 $101.67 3,400,001 $650.0 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 par for cash at our option. 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 In February 2015, 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 SL Green's common stock under the DRSPP. The DRSPP commenced on September 24, 2001. Earnings per Share SL Green's earnings per share for the three and nine months ended September 30, 2017 and 2016 are computed as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Numerator 2017 2016 2017 2016 Basic Earnings: Income attributable to SL Green common stockholders $ 38,869 $ 34,252 $ 58,442 $ 190,930 Effect of Dilutive Securities: Redemption of units to common shares 1,812 1,663 2,707 8,171 Diluted Earnings: Income attributable to SL Green common stockholders $ 40,681 $ 35,915 $ 61,149 $ 199,101 Three Months Ended September 30, Nine Months Ended September 30, Denominator 2017 2016 2017 2016 Basic Shares: Weighted average common stock outstanding 97,783 100,233 99,431 100,140 Effect of Dilutive Securities: Operating Partnership units redeemable for common shares 4,543 4,497 4,570 4,272 Stock-based compensation plans 244 413 279 349 Diluted weighted average common stock outstanding 102,570 105,143 104,280 104,761 SL Green has excluded 1,175,708 and 1,076,695 common stock equivalents from the diluted shares outstanding for the three and nine months ended September 30, 2017 , respectively, as they were anti-dilutive. SL Green has excluded 673,298 and 753,344 common stock equivalents from the diluted shares outstanding for the three and nine months ended September 30, 2016 , respectively, as they were anti-dilutive.
SL Green Realty Corp
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income	Accumulated Other Comprehensive Income The following tables set forth the changes in accumulated other comprehensive income (loss) by component as of September 30, 2017 (in thousands): Net unrealized gain on derivative instruments ( 1 ) SL Green’s share of joint venture net unrealized gain on derivative instruments ( 2 ) Net unrealized gain on marketable securities Total Balance at December 31, 2016 $ 12,596 $ 4,021 $ 5,520 $ 22,137 Other comprehensive (loss) before reclassifications (4,669 ) (947 ) (1,133 ) (6,749 ) Amounts reclassified from accumulated other comprehensive income 1,336 591 (3,130 ) (1,203 ) Balance at September 30, 2017 $ 9,263 $ 3,665 $ 1,257 $ 14,185 (1) Amount reclassified from accumulated other comprehensive income (loss) is included in interest expense in the respective consolidated statements of operations. As of September 30, 2017 and December 31, 2016 , the deferred net losses from these terminated hedges, which is included in accumulated other comprehensive loss relating to net unrealized loss on derivative instrument, was $3.7 million and $7.1 million , respectively. (2) Amount reclassified from accumulated other comprehensive income (loss) is included in equity in net income from unconsolidated joint ventures in the respective consolidated statements of operations.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We 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 September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 Total Level 1 Level 2 Level 3 Assets: Marketable securities $ 28,802 $ — $ 28,802 $ — Interest rate cap and swap agreements (included in other assets) $ 13,727 $ — $ 13,727 $ — December 31, 2016 Total Level 1 Level 2 Level 3 Assets: Marketable securities $ 85,110 $ 48,315 $ 36,795 $ — Interest rate cap and swap agreements (included in other assets) $ 21,090 $ — $ 21,090 $ — Liabilities: Interest rate cap and swap agreements (included in accrued interest payable and other liabilities) $ 1 $ — $ 1 $ — We determine other than temporary impairment in real estate investments and debt and preferred equity investments, including intangibles 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. As of September 30, 2017, we held notes receivable totaling $250.0 million , which were purchased at par, and were in maturity default at the time of acquisition. In August 2017, the Company determined that it was probable that the loans would not be repaid in full and therefore, the loans were put on non-accrual status. The Company has initiated proceedings to foreclose on the property, and expects to take control of the property unless the buyer is able to repay the principal and interest, including default interest and fees, on the notes receivable in full prior to the completion of the foreclosure process. We believe the collateral value is sufficient to recover the carrying amounts of the notes receivable. The marketable securities classified as Level 1 were derived from quoted prices in active markets. The valuation technique used to measure the fair value of the 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. Marketable securities in an unrealized loss position are not considered to be other than temporarily impaired. 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 September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Carrying Value (1) Fair Value Carrying Value (1) Fair Value Debt and preferred equity investments $ 2,020,739 (2) $ 1,640,412 (2) Fixed rate debt $ 5,154,810 $ 5,398,870 $ 5,452,084 $ 5,722,494 Variable rate debt 1,321,813 1,314,223 1,105,585 1,110,110 $ 6,476,623 $ 6,713,093 $ 6,557,669 $ 6,832,604 (1) Amounts exclude net deferred financing costs. (2) At September 30, 2017 , debt and preferred equity investments had an estimated fair value ranging between $2.0 billion and $2.2 billion . At December 31, 2016 , debt and preferred equity investments had an estimated fair value ranging between $1.6 billion and $1.8 billion . Disclosure about fair value of financial instruments was based on pertinent information available to us as of September 30, 2017 and December 31, 2016 . Although we are not aware of any factors that would significantly affect the reasonable fair value amounts, 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	9 Months Ended
	Sep. 30, 2017
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 sheets 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 until the hedged item is recognized in earnings. The ineffective portion of a derivative's change in fair value will be immediately 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 September 30, 2017 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 (amounts in thousands). Notional Value Strike Rate Effective Date Expiration Date Balance Sheet Location Fair Value Interest Rate Swap $ 200,000 0.938 % October 2014 December 2017 Other Assets $ 105 Interest Rate Swap 150,000 0.940 % October 2014 December 2017 Other Assets 78 Interest Rate Swap 150,000 0.940 % October 2014 December 2017 Other Assets 78 Interest Rate Cap 137,500 4.000 % September 2017 September 2019 Other Assets 4 Interest Rate Swap 200,000 1.131 % July 2016 July 2023 Other Assets 8,998 Interest Rate Swap 100,000 1.161 % July 2016 July 2023 Other Assets 4,335 Interest Rate Swap 100,000 2.287 % November 2017 November 2027 Other Assets 129 $ 13,727 During both the three and nine months ended September 30, 2017 , we recorded a loss on the changes in the fair value of $0.1 million , which is included in interest expense on the consolidated statements of operations. During the three and nine months ended September 30, 2016 , we recorded a $0.1 million loss and a $0.5 million gain, respectively, on the changes in the fair value, which is included in interest expense on the consolidated statements of operations. The Company has agreements with each of its derivative counterparties that contain a provision where if the Company either defaults or is capable of being declared in default on any of its indebtedness, then the Company could also be declared in default on its derivative obligations. As of September 30, 2017 , 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 zero . As of September 30, 2017 , the Company has 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 zero at September 30, 2017 . Gains and losses on terminated hedges are included in accumulated other comprehensive 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 $0.8 million of the current balance held in accumulated other comprehensive loss will be reclassified into interest expense and $0.3 million of the portion related to our share of joint venture accumulated other comprehensive loss will be reclassified into equity in net income 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 September 30, 2017 and 2016 , respectively (in thousands): Amount of (Loss) Location of (Loss) Reclassified from Accumulated Other Comprehensive Loss into Income Amount of Loss Location of (Loss) Recognized in Income on Derivative Amount of (Loss) Gain Three Months Ended September 30, Three Months Ended September 30, Three Months Ended September 30, Derivative 2017 2016 2017 2016 2017 2016 Interest Rate Swaps/Caps $ (304 ) $ (7 ) Interest expense $ 85 $ 1,442 Interest expense $ 4 $ — Share of unconsolidated joint ventures' derivative instruments (290 ) (222 ) Equity in net income from unconsolidated joint ventures 185 547 Equity in net income from unconsolidated joint ventures (48 ) 830 $ (594 ) $ (229 ) $ 270 $ 1,989 $ (44 ) $ 830 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 nine months ended September 30, 2017 and 2016 , respectively (in thousands): Amount of (Loss) Recognized in Location of (Loss) Reclassified from Accumulated Other Comprehensive Loss into Income Amount of Loss Location of (Loss) Recognized in Income on Derivative Amount of (Loss) Nine Months Ended September 30, Nine Months Ended September 30, Nine Months Ended September 30, Derivative 2017 2016 2017 2016 2017 2016 Interest Rate Swaps/Caps $ (5,477 ) $ (8,112 ) Interest expense $ 1,583 $ 8,073 Interest expense $ (4 ) $ (38 ) Share of unconsolidated joint ventures' derivative instruments (1,277 ) (5,992 ) Equity in net income from unconsolidated joint ventures 876 1,465 Equity in net income from unconsolidated joint ventures (109 ) (206 ) $ (6,754 ) $ (14,104 ) $ 2,459 $ 9,538 $ (113 ) $ (244 )

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings As of September 30, 2017 , 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. Capital and Ground Leases Arrangements The following is a schedule of future minimum lease payments under capital leases and non-cancellable operating leases with initial terms in excess of one year as of September 30, 2017 (in thousands): Capital lease Non-cancellable operating leases Remaining 2017 $ 597 $ 7,763 2018 2,387 31,049 2019 2,411 31,066 2020 2,620 31,436 2021 2,794 31,628 Thereafter 822,688 732,724 Total minimum lease payments $ 833,497 $ 865,666 Amount representing interest (790,837 ) Capital lease obligations $ 42,660

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information The Company is a REIT with in-house capabilities in commercial and residential property management, acquisitions and dispositions, financing, development and redevelopment, construction and leasing in the New York Metropolitan area, and has two reportable segments, real estate and debt and preferred equity investments. We evaluate real estate performance and allocate resources based on earnings contribution to income from continuing operations. 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 and nine months ended September 30, 2017 and 2016 , and selected asset information as of September 30, 2017 and December 31, 2016 , regarding our operating segments are as follows (in thousands): Real Estate Segment Debt and Preferred Equity Segment Total Company Total revenues Three months ended: September 30, 2017 $ 326,780 $ 47,820 $ 374,600 September 30, 2016 341,285 75,396 416,681 Nine months ended: September 30, 2017 1,001,390 148,741 1,150,131 September 30, 2016 1,315,392 174,347 1,489,739 Net income (loss) before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain on sale of real estate, net, depreciable real estate reserves, and gain on sale of investment in marketable securities Three months ended: September 30, 2017 $ 4,873 $ 39,892 $ 44,765 September 30, 2016 (32,731 ) 75,452 42,721 Nine months ended: September 30, 2017 (504 ) 132,402 131,898 September 30, 2016 (187,222 ) 168,295 (18,927 ) Total assets As of: September 30, 2017 $ 12,939,363 $ 2,170,507 $ 15,109,870 December 31, 2016 13,868,672 1,989,115 15,857,787 Income from continuing operations represents total revenues less total expenses for the real estate segment and total investment income less allocated interest expense for the debt and preferred equity segment. Interest costs for the debt and preferred equity segment includes actual costs incurred for borrowings on the 2016 MRA and 2017 MRA. Interest is imputed on the investments that do not collateralize the 2016 MRA or 2017 MRA using our 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 since the use of personnel and resources is dependent on transaction volume between the two segments and varies period over period. In addition, we base performance on the individual segments prior to allocating marketing, general and administrative expenses. For the three and nine months ended September 30, 2017 , marketing, general and administrative expenses totaled $24.0 million , and $72.4 million respectively. For the three and nine months ended September 30, 2016 , marketing, general and administrative expenses totaled $25.5 million and $74.0 million , respectively. All other expenses, except interest, relate entirely to the real estate assets. There were no transactions between the above two segments. The table below reconciles income from continuing operations to net income for the three and nine months ended September 30, 2017 and 2016 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Net income (loss) before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain on sale of real estate, net, depreciable real estate reserves, and gain on sale of investment in marketable securities $ 44,765 $ 42,721 $ 131,898 $ (18,927 ) Equity in net gain on sale of interest in unconsolidated joint venture/real estate 1,030 225 16,166 43,588 Gain (loss) on sale of real estate, net — 397 (3,256 ) 210,750 Depreciable real estate reserves — — (85,336 ) (10,387 ) Gain (loss) on sale of investment in marketable securities — — 3,262 (83 ) Net income $ 45,795 $ 43,343 $ 62,734 $ 224,941

Significant Accounting Polici32

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
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 variable interest entity, or 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 On a periodic basis, we assess whether there are any indications that the value of our real estate properties may be other than temporarily 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 calculated fair value of the property. We also evaluate our real estate properties for potential impairment when a real estate property has been classified as held for sale. Real estate assets held for sale are valued at the lower of either their carrying value or fair value less costs to sell. We do not believe that there were any indicators of impairment at any of our consolidated properties at September 30, 2017 . We recorded no depreciable real estate reserves for the three months ended September 30, 2017 , and aggregate depreciable real estate reserves of $85.3 million for the nine months ended September 30, 2017 . See Note 4, "Property Dispositions". 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 three 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 one to 14 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 one to 14 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 and capitalization 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.
Fair Value Measurements	Fair Value Measurements We 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 determine other than temporary impairment in real estate investments and debt and preferred equity investments, including intangibles 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. As of September 30, 2017, we held notes receivable totaling $250.0 million , which were purchased at par, and were in maturity default at the time of acquisition. In August 2017, the Company determined that it was probable that the loans would not be repaid in full and therefore, the loans were put on non-accrual status. The Company has initiated proceedings to foreclose on the property, and expects to take control of the property unless the buyer is able to repay the principal and interest, including default interest and fees, on the notes receivable in full prior to the completion of the foreclosure process. We believe the collateral value is sufficient to recover the carrying amounts of the notes receivable. The marketable securities classified as Level 1 were derived from quoted prices in active markets. The valuation technique used to measure the fair value of the 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. Marketable securities in an unrealized loss position are not considered to be other than temporarily impaired. 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.
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 September 30, 2017 , 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 Accounting Standards Codification, or ASC, 820-10, with the net unrealized gains or losses reported as a component of accumulated other comprehensive income or loss. Any unrealized losses that are determined to be other-than-temporary are recognized in earnings up to their credit component. The cost of bonds and marketable securities sold is determined using the specific identification method.
Investments in Unconsolidated Joint Ventures	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 the joint ventures' projected discounted cash flows.
Reserve for Possible Credit Losses	Reserve for Possible Credit Losses The expense for possible credit losses in connection with debt and preferred equity investments is the charge to earnings to increase the allowance for possible credit losses to the level that we estimate to be adequate, based on Level 3 data, considering delinquencies, loss experience and collateral quality. Other factors considered include geographic trends, product diversification, the size of the portfolio and current economic conditions. Based upon these factors, we establish a provision for possible credit loss on each individual investment. When it is probable that we will be unable to collect all amounts contractually due, the investment is considered impaired. Where impairment is indicated on an investment that is held to maturity, a valuation allowance is measured based upon the excess of the recorded investment amount over the net fair value of the collateral. Any deficiency between the carrying amount of an asset and the calculated value of the collateral is charged to expense. We continue to assess or adjust our estimates based on circumstances of a loan and the underlying collateral. If additional information reflects increased recovery of our investment, we will adjust our reserves accordingly.
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 SL Green's 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 SL Green's 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. Pursuant to amendments to the Code that became effective January 1, 2001, we have elected, and may elect in the future, to treat certain of our existing or newly created 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 and nine months ended September 30, 2017 , we recorded Federal, state and local tax provisions of $0.1 million and $2.8 million , respectively. 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." We perform ongoing credit evaluations 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 source of funds to offset the economic costs associated with lost revenue and the costs associated with re-tenanting a space.
Reclassification	Reclassification Certain prior year balances have been reclassified to conform to our current year presentation.
Accounting Standards Updates	resentation. Accounting Standards Updates In August 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-12, Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities. The amendments in the new standard will permit more flexibility in hedging interest rate risk for both variable rate and fixed rate financial instruments. The standard will also enhance the presentation of hedge results in the financial statements. The guidance is effective for fiscal years beginning after December 15, 2018 and early adoption is permitted. The Company has not yet adopted the guidance, and does not expect a material impact on the Company’s consolidated financial statements when the new standard is implemented. In May 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-09, Compensation - Stock Compensation (Topic 718), Scope of Modification Accounting. The guidance clarifies the changes to the terms or conditions of a share-based payment award that require an entity to apply modification accounting in Topic 718. The guidance is effective for fiscal years beginning after December 15, 2017 and early adoption is permitted. The Company has not yet adopted the guidance. In February 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-05 to clarify the scope of Subtopic 610-20 as well as provide guidance on accounting for partial sales of nonfinancial assets. Subtopic 610-20 was issued in May 2014 as part of ASU 2014-09. The Company anticipates adopting this guidance January 1, 2018, and applying the modified retrospective approach. The Company is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In January, 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. The guidance clarifies the definition of a business and provides guidance to assist with determining whether transactions should be accounted for as acquisitions of assets or businesses. The main provision is that an acquiree is not a business if substantially all of the fair value of the gross assets is concentrated in a single identifiable asset or group of assets. The Company adopted the guidance on the issuance date effective January 5, 2017. The Company expects that most of our real estate acquisitions will be considered asset acquisitions under the new guidance and that transaction costs will be capitalized to the investment basis which is then subject to a purchase price allocation based on relative fair value. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The guidance will require entities to show the changes on the total cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between these items on the statement of cash flows. The guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The ASU provides final guidance on eight cash flow issues, including debt prepayment or debt extinguishment costs, contingent consideration payments made after a business combination, distributions received from equity method investees, separately identifiable cash flows and application of the predominance principle, and others. The amendments in the ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company adopted the guidance effective January 1, 2017 and there was no impact on the Company’s consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The guidance changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance replaces the current ‘incurred loss’ model with an ‘expected loss’ approach. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted after December 2018. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The guidance simplifies the accounting for share-based payment award transactions including: income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The guidance is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted. The Company adopted the guidance effective January 1, 2017 and there was no material impact on the Company’s consolidated financial statements. In March 2016, the FASB issued ASU 2016-07, Investments Equity Method and Joint Ventures (Topic 323). The guidance eliminates the requirement that an entity retroactively adopt the equity method of accounting if an investment qualifies for use of the equity method as a result of an increase in the level of ownership or degree of influence. The amendments require that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor’s previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. The Company adopted the guidance effective January 1, 2017 and there was no impact on the Company’s consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases. The guidance requires lessees to recognize lease assets and lease liabilities for those leases classified as operating leases under the previous standard. Depending on the lease classification, lessees will recognize expense based on the effective interest method for finance leases or on a straight-line basis for operating leases. The accounting applied by a lessor is largely unchanged from that applied under the previous standard. One of the impacts on the Company will be the presentation and disclosure in the financial statements of non-lease components such as charges to tenants for a building’s operating expenses. The non-lease components will be presented separately from the lease components in both the Consolidated Statements of Operations and Consolidated Balance Sheets. Another impact is the measurement and presentation of ground leases under which the Company is lessee. The Company is required to record a liability for the obligation to make payments under the lease and an asset for the right to use the underlying asset during the lease term and will also apply the new expense recognition requirements given the lease classification. The Company is currently quantifying these impacts. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The Company anticipates adopting this guidance January 1, 2019 and will apply the modified retrospective approach. In January 2016, the FASB issued ASU 2016-01 (Subtopic 825-10), Recognition and Measurement of Financial Assets and Financial Liabilities. The guidance requires entities to measure equity investments that do not result in consolidation and are not accounted for under the equity method at fair value and to record changes in instruments-specific credit risk for financial liabilities measured under the fair value option in other comprehensive income. The guidance is effective for fiscal years beginning after December 15, 2017, and for interim periods therein. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In May 2014, the FASB issued a new comprehensive revenue recognition guidance which requires us to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods and services (ASU 2014-09). The FASB also issued implementation guidance in March 2016, April 2016 and May 2016 - ASU’s 2016-08, 2016-10 and 2016-12, respectively. These ASUs are effective for annual and interim periods beginning after December 15, 2017. The Company will adopt this guidance January 1, 2018. Since the Company’s revenue is related to leasing activities, the adoption of this guidance will not have a material impact on the consolidated financial statements. The new guidance is applicable to service contracts with joint ventures for which the Company earns property management fees, leasing commissions and development and construction fees. The adoption of this new guidance does not change the accounting for these fees as the pattern of recognition of revenue does not change with the new guidance. We will continue to recognize revenue over time on these contracts because the customer simultaneously receives and consumes the benefits provided by our performance. Thus, the analysis of our contracts under the new revenue recognition standard is consistent with our current revenue recognition model

Organization and Basis of Pre33

Organization and Basis of Presentation (Tables)	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of commercial office properties	As of September 30, 2017 , we owned the following interests in properties in the New York Metropolitan area, primarily in midtown Manhattan. Our investments in the New York Metropolitan area also include investments in Brooklyn, Long Island, Westchester County, Connecticut and New Jersey, which are collectively known as the Suburban properties: Consolidated Unconsolidated Total Location Property Number of Properties Approximate Square Feet (unaudited) Number of Properties Approximate Square Feet (unaudited) Number of Properties Approximate Square Feet (unaudited) Weighted Average Occupancy (1) (unaudited) Commercial: Manhattan Office 24 16,054,606 7 6,558,139 31 22,612,745 93.4 % Retail 4 (2) 302,583 9 347,970 13 650,553 94.5 % Development/Redevelopment 7 158,985 4 770,514 11 929,499 59.9 % Fee Interest 1 176,530 1 — 2 176,530 100.0 % 36 16,692,704 21 7,676,623 57 24,369,327 92.2 % Suburban Office 22 (3)(4) 3,608,800 2 640,000 24 4,248,800 83.1 % Retail 1 52,000 — — 1 52,000 100.0 % Development/Redevelopment 1 1,000 1 — 2 1,000 100.0 % 24 3,661,800 3 640,000 27 4,301,800 83.3 % Total commercial properties 60 20,354,504 24 8,316,623 84 28,671,127 90.8 % Residential: Manhattan Residential 3 (2) 472,105 12 2,656,856 15 3,128,961 86.4 % Suburban Residential — — — — — — — % Total residential properties 3 472,105 12 2,656,856 15 3,128,961 86.4 % Total portfolio (2)(3) 63 20,826,609 36 10,973,479 99 31,800,088 90.4 % (1) The weighted average occupancy for commercial properties represents the total occupied square feet divided by total square footage at acquisition. The weighted average occupancy for residential properties represents the total occupied units divided by total available units. (2) As of September 30, 2017 , we owned a building at 315 West 33rd Street, also known as The Olivia, that was comprised of approximately 270,132 square feet (unaudited) of retail space and approximately 222,855 square feet (unaudited) of residential space. For the purpose of this report, we have included this building in the number of retail properties we own. However, we have included only the retail square footage in the retail approximate square footage, and have listed the balance of the square footage as residential square footage. (3) Includes the properties at 16 Court Street in Brooklyn, New York, and 125 Chubb Avenue in Lyndhurst, New Jersey which are classified as held for sale at September 30, 2017. The sales closed in October 2017.

Significant Accounting Polici34

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Identified intangible assets (included in other assets): Gross amount $ 474,493 $ 651,099 Accumulated amortization (398,047 ) (410,930 ) Net (1) $ 76,446 $ 240,169 Identified intangible liabilities (included in deferred revenue): Gross amount $ 639,511 $ 655,930 Accumulated amortization (474,365 ) (464,749 ) Net (1) $ 165,146 $ 191,181 (1) As of September 30, 2017 and December 31, 2016, $3.9 million and none , respectively and $1.1 million and none , respectively, of net intangible assets and net intangible liabilities, were reclassified to assets held for sale and liabilities related to assets held for sale.
Schedule of marketable securities	At September 30, 2017 and December 31, 2016 , we held the following marketable securities (in thousands): September 30, 2017 December 31, 2016 Equity marketable securities $ — $ 48,315 Commercial mortgage-backed securities 28,802 36,795 Total marketable securities available-for-sale $ 28,802 $ 85,110

Properties Held for Sale and 35

Properties Held for Sale and Property Dispositions (Tables)	9 Months Ended
	Sep. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Summary of properties sold	The following table summarizes the properties sold during the nine months ended September 30, 2017 : Property Disposition Date Property Type Approximate Square Feet Sales Price (1) (in millions) Gain (loss) (2) (in millions) 885 Third Avenue (3) February 2016 Fee Interest 607,000 $ 453.0 $ (8.8 ) 520 White Plains Road April 2017 Office 180,000 21.0 (14.6 ) 102 Greene Street (4) April 2017 Retail 9,200 43.5 4.9 680-750 Washington Boulevard July 2017 Office 325,000 97.0 (44.2 ) (1) Sales price represents the gross sales price for a property or the gross asset valuation for interests in a property. (2) The gain on sale for 102 Greene Street is net of $0.9 million in employee compensation awards accrued in connection with the realization of the investment gain as a bonus to certain employees that were instrumental in realizing the gain on sale. Additionally, gain on sale amounts do not include adjustments for expenses recorded in subsequent periods. (3) In February 2016, we closed on the sale of 885 Third Avenue. The sale did not meet the criteria for sale accounting and as a result the property remained on our consolidated financial statements until the criteria was met in April 2017. (4) In April 2017, we closed on the sale of a 90% interest 102 Greene Street and had subsequently accounted for our interest in the property as an investment in unconsolidated joint ventures. We sold the remaining 10% interest in September 2017. See Note 6, "Investments in Unconsolidated Joint Ventures".

Debt and Preferred Equity Inv36

Debt and Preferred Equity Investments (Tables)	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule of debt and preferred equity book balance roll forward	Below is the rollforward analysis of the activity relating to our debt and preferred equity investments as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Balance at beginning of period (1) $ 1,640,412 $ 1,670,020 Debt Investment Originations/Accretion (2) 944,494 1,009,176 Preferred Equity Investment Originations/Accretion (2) 144,013 5,698 Redemptions/Sales/Syndications/Amortization (3) (708,180 ) (1,044,482 ) Balance at end of period (1) $ 2,020,739 $ 1,640,412 (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 did not meet the conditions for sale accounting are included in other assets and other liabilities on the consolidated balance sheets.
Summary of debt investments	As of September 30, 2017 and December 31, 2016 , we held the following debt investments with an aggregate weighted average current yield of 9.49% , excluding our investment in Two Herald Square, at September 30, 2017 (in thousands): Loan Type September 30, 2017 Future Funding Obligations September 30, 2017 Senior September 30, 2017 (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Fixed Rate Investments: Mortgage/Jr. Mortgage Loan (3) $ — $ — $ 250,164 $ — April 2017 Mortgage Loan (4) — — 26,352 26,311 February 2019 Mortgage Loan — — 275 380 August 2019 Mezzanine Loan (5a) — 1,160,000 201,757 — March 2020 Mezzanine Loan — 15,000 3,500 3,500 September 2021 Mezzanine Loan — 147,000 24,909 — April 2022 Mezzanine Loan — 87,595 12,697 12,692 November 2023 Mezzanine Loan (5b) — 115,000 12,930 12,925 June 2024 Mezzanine Loan — 95,000 30,000 30,000 January 2025 Mezzanine Loan — 340,000 15,000 15,000 November 2026 Mezzanine Loan — 1,657,500 55,250 — June 2027 Mezzanine Loan (6) — — — 66,129 Jr. Mortgage Participation/Mezzanine Loan (7) — — — 193,422 Total fixed rate $ — $ 3,617,095 $ 632,834 $ 360,359 Floating Rate Investments: Mortgage/Mezzanine Loan (8) 622 — 23,372 20,423 October 2017 Mezzanine Loan (5c) — 85,000 15,340 15,141 December 2017 Mezzanine Loan (5d) — 65,000 14,832 14,656 December 2017 Mezzanine Loan (5e) 795 — 15,132 15,051 December 2017 Mortgage/Mezzanine Loan (9) — 125,000 29,966 29,998 January 2018 Mezzanine Loan — 40,000 19,964 19,913 April 2018 Jr. Mortgage Participation — 117,808 34,899 34,844 April 2018 Mezzanine Loan 523 20,523 10,916 10,863 August 2018 Mortgage/Mezzanine Loan — — 19,914 19,840 August 2018 Mortgage Loan — 65,000 14,935 14,880 August 2018 Loan Type September 30, 2017 Future Funding Obligations September 30, 2017 Senior September 30, 2017 (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Mortgage/Mezzanine Loan (10) — — 16,957 16,960 September 2018 Mezzanine Loan — 37,500 14,801 14,648 September 2018 Mezzanine Loan 2,325 45,025 34,782 34,502 October 2018 Mezzanine Loan — 335,000 74,683 74,476 November 2018 Mezzanine Loan — 33,000 26,907 26,850 December 2018 Mezzanine Loan 1,050 171,939 58,598 56,114 December 2018 Mezzanine Loan 8,267 289,621 71,067 63,137 December 2018 Mezzanine Loan 5,197 229,084 74,314 64,505 December 2018 Mezzanine Loan — 45,000 12,156 12,104 January 2019 Mortgage/Mezzanine Loan (5f) 30,101 — 158,757 — January 2019 Mezzanine Loan 6,081 24,086 7,812 5,410 January 2019 Mezzanine Loan — 38,000 21,927 21,891 March 2019 Mezzanine Loan 279 173,700 36,936 — April 2019 Mezzanine Loan — 265,000 24,798 24,707 April 2019 Mortgage/Jr. Mortgage Participation Loan 29,661 194,094 69,705 65,554 August 2019 Mezzanine Loan 2,034 187,500 37,835 37,322 September 2019 Mortgage/Mezzanine Loan 49,933 — 130,350 111,819 September 2019 Mortgage/Mezzanine Loan 30,494 — 38,934 33,682 January 2020 Mezzanine Loan (11) 6,794 537,748 72,597 125,911 January 2020 Mezzanine Loan 7,164 33,587 10,988 — July 2020 Jr. Mortgage Participation/Mezzanine Loan — 60,000 15,627 15,606 July 2021 Mezzanine Loan — 280,000 34,124 — August 2022 Mezzanine Loan (12) — — — 15,369 Mortgage/ Mezzanine Loan (6) — — — 32,847 Mortgage/Mezzanine Loan (6) — — — 22,959 Mezzanine Loan (13) — — — 14,957 Mortgage/Mezzanine Loan (14) — — — 145,239 Total floating rate $ 181,320 $ 3,498,215 $ 1,243,925 $ 1,232,178 Total $ 181,320 $ 7,115,310 $ 1,876,759 $ 1,592,537 (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) These loans were purchased at par in April and May 2017 and were in maturity default at the time of acquisition. At the time the loans were purchased, the Company expected to collect all contractually required payments, including interest. In August 2017, the Company determined that it was probable that the loans would not be repaid in full and therefore, the loans were put on non-accrual status. No impairment was recorded as the Company believes that the fair value of the property exceeds the carrying amount of the loans. The loans had an outstanding balance including accrued interest of $259.3 million at the time that they were put on non-accrual status. (4) In September 2014, we acquired a $26.4 million mortgage loan at a $0.2 million discount and a $5.7 million junior mortgage participation at a $5.7 million discount. The junior mortgage participation was a nonperforming loan at acquisition, is currently on non-accrual status and has no carrying value. (5) 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) $1.2 million , (b) $12.0 million , (c) $14.6 million , (d) $14.1 million , (e) $5.1 million , and (f) $21.2 million (6) This loan was repaid in June 2017. (7) This loan was repaid in March 2017. (8) This loan was extended in October 2017. (9) This loan was extended in January 2017. (10) This loan was extended in September 2017. (11) $66.1 million of outstanding principal was syndicated in February 2017. (12) This loan was repaid in September 2017. (13) This loan was contributed to a joint venture in May 2017. (14) This loan was repaid in January 2017.
Summary of preferred equity investments	As of September 30, 2017 and December 31, 2016 , we held the following preferred equity investments with an aggregate weighted average current yield of 6.98% at September 30, 2017 (in thousands): Type September 30, 2017 September 30, 2017 September 30, 2017 (1) December 31, 2016 (1) Mandatory Redemption (2) Preferred Equity (3) $ — $ 272,000 $ 143,980 $ — April 2021 Preferred Equity (4) — — — 9,982 Preferred Equity (5) — — — 37,893 Total $ — $ 272,000 $ 143,980 $ 47,875 (1) Carrying value is net of deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options. (3) In February 2016, we closed on the sale of 885 Third Avenue and retained a preferred equity position in the property. The sale did not meet the criteria for sale accounting under the full accrual method in ASC 360-20, Property, Plant and Equipment - Real Estate Sales. As a result the property remained on our consolidated balance sheet until the criteria was met in April 2017 at which time the property was deconsolidated and the preferred equity investment was recognized. (4) This investment was redeemed in May 2017. (5) This investment was redeemed in April 2017.

Investments in Unconsolidated37

Investments in Unconsolidated Joint Ventures (Tables)	9 Months Ended
	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Schedule of general information on joint ventures	The following table summarizes the investments in unconsolidated joint ventures sold during the nine months ended September 30, 2017 : Property Ownership Interest Disposition Date Type of Sale Gross Asset Valuation (in thousands) (1) Gain on Sale (in thousands) (2) Stonehenge Portfolio (partial) Various March 2017 Ownership Interest $ 300,000 $ 871 102 Greene Street 10.00% September 2017 Ownership Interest $ 43,500 $ 283 (1) Represents implied gross valuation for the joint venture or sales price of the property. (2) Represents the Company's share of the gain. The table below provides general information on each of our joint ventures as of September 30, 2017 : Property Partner Ownership (1) Economic (1) Unaudited Approximate Square Feet Acquisition Date (2) Acquisition (2) (in thousands) 100 Park Avenue Prudential Real Estate Investors 49.90% 49.90% 834,000 February 2000 $ 95,800 717 Fifth Avenue Jeff Sutton/Private Investor 10.92% 10.92% 119,500 September 2006 251,900 800 Third Avenue Private Investors 60.52% 60.52% 526,000 December 2006 285,000 1745 Broadway Ivanhoe Cambridge, Inc. 56.87% 56.87% 674,000 April 2007 520,000 Jericho Plaza Onyx Equities/Credit Suisse 11.67% 11.67% 640,000 April 2007 210,000 11 West 34th Street Private Investor/ 30.00% 30.00% 17,150 December 2010 10,800 3 Columbus Circle (3) The Moinian Group 48.90% 48.90% 741,500 January 2011 500,000 280 Park Avenue Vornado Realty Trust 50.00% 50.00% 1,219,158 March 2011 400,000 1552-1560 Broadway (4) Jeff Sutton 50.00% 50.00% 57,718 August 2011 136,550 724 Fifth Avenue Jeff Sutton 50.00% 50.00% 65,010 January 2012 223,000 10 East 53rd Street Canadian Pension Plan Investment Board 55.00% 55.00% 354,300 February 2012 252,500 521 Fifth Avenue Plaza Global 50.50% 50.50% 460,000 November 2012 315,000 21 East 66th Street (5) Private Investors 32.28% 32.28% 13,069 December 2012 75,000 650 Fifth Avenue (6) Jeff Sutton 50.00% 50.00% 69,214 November 2013 — 121 Greene Street Jeff Sutton 50.00% 50.00% 7,131 September 2014 27,400 175-225 Third Street Brooklyn, New York KCLW 3rd Street LLC/LIVWRK LLC 95.00% 95.00% — October 2014 74,600 55 West 46th Street Prudential Real Estate Investors 25.00% 25.00% 347,000 November 2014 295,000 Stonehenge Portfolio (7) Various Various Various 1,439,016 February 2015 36,668 131-137 Spring Street Invesco Real Estate 20.00% 20.00% 68,342 August 2015 277,750 605 West 42nd Street The Moinian Group 20.00% 20.00% 927,358 April 2016 759,000 11 Madison Avenue PGIM Real Estate 60.00% 60.00% 2,314,000 August 2016 2,605,000 333 East 22nd Street (8) Private Investors 33.33% 33.33% 26,926 August 2016 — 400 E 57th Street (9) BlackRock, Inc and Stonehenge Partners 51.00% 41.00% 290,482 October 2016 170,000 One Vanderbilt (10) National Pension Service of Korea/Hines Interest LP 71.01% 71.01% — January 2017 3,310,000 Mezzanine Loan (11) Private Investors 33.33% 33.33% — May 2017 15,000 (1) Ownership interest and economic interest represent the Company's interests in the joint venture as of September 30, 2017 . Changes in ownership or economic interests, if any, within the current year are disclosed in the notes below. (2) Acquisition date and price represent the date on which the Company initially acquired an interest in the joint venture and the actual or implied gross purchase price for the joint venture on that date. Acquisition date and price are not adjusted for subsequent acquisitions or dispositions of interest. (3) As a result of the sale of a condominium interest in September 2012, Young & Rubicam, Inc., or Y&R, owns floors three through eight at the property. Because the joint venture has an option to repurchase these floors, the gain associated with this sale was deferred. (4) The purchase price represents only the purchase of the 1552 Broadway interest which comprised approximately 13,045 square feet. 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. (5) We hold a 32.28 % interest in three retail and two residential units at the property and a 16.14 % interest in three residential units at the property. (6) The joint venture owns a long-term leasehold interest in the retail space at 650 Fifth Avenue. In connection with the ground lease obligation, SLG provided a performance guaranty and our joint venture partner executed a contribution agreement to reflect its pro rata obligation. In the event the property is converted into a condominium unit and the landlord elects the purchase option, the joint venture shall be obligated to acquire the unit at the then fair value. (7) In March 2017, the Company sold a partial interest in the Stonehenge Portfolio as further described under Sale of Joint Venture Interest or Properties below. (8) The joint venture acquired a leasehold interest in the property in October 2016. (9) In October 2016, the Company sold a 49% interest in this property to an investment account managed by BlackRock, Inc. The Company's 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. The Company's joint venture with Stonehenge remains consolidated resulting in the combined 51% interest being shown within investments in unconsolidated joint ventures on the Company's balance sheet. (10) In January 2017, the Company admitted two partners, National Pension Service of Korea and Hines Interest LP, into the One Vanderbilt Avenue development project. In April 2017, the criteria for deconsolidation were met, and the development is shown within investments in unconsolidated joint ventures. The partners have committed aggregate equity to the project totaling no less than $525 million and their ownership interest in the joint venture is based on their capital contributions, up to an aggregate maximum of 29.0% . At September 30, 2017 the total of the two partners' ownership interests based on equity contributed was 3.49% . (11) In May 2017, the Company contributed a mezzanine loan secured by a commercial property in midtown Manhattan to a joint venture and retained a 33.33% interest in the venture. The carrying value is net of $10.0 million that was sold, which is 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. In October 2017, the initial maturity date of November 2017 was extended to November 2018. As of September 30, 2017 and December 31, 2016, the carrying value for acquisition, development and construction arrangements were as follows (in thousands): Loan Type September 30, 2017 December 31, 2016 Maturity Date Mezzanine Loan and Preferred Equity (1) $ 100,000 $ 100,000 March 2018 Mezzanine Loan (2) 44,881 45,622 February 2022 Mezzanine Loan (3) 25,854 24,542 July 2036 $ 170,735 $ 170,164 (1) These loans were extended in February 2017. (2) We have an option to convert our loan to an equity interest subject to certain conditions. We have determined that our option to convert the loan to equity is not a derivative financial instrument pursuant to GAAP. (3) The Company has the ability to convert this loan into an equity position starting in 2021 and the borrower is able to force this conversion in 2024.
Schedule of first mortgage notes payable collateralized by the respective joint venture properties and assignment of leases	The first mortgage notes and other loans payable collateralized by the respective joint venture properties and assignment of leases at September 30, 2017 and December 31, 2016 , respectively, are as follows (amounts in thousands): Property Economic (1) Maturity Date Interest Rate (2) September 30, 2017 December 31, 2016 Fixed Rate Debt: 521 Fifth Avenue 50.50 % November 2019 3.73 % $ 170,000 $ 170,000 717 Fifth Avenue (3) 10.92 % July 2022 4.45 % 300,000 300,000 Property Economic (1) Maturity Date Interest Rate (2) September 30, 2017 December 31, 2016 717 Fifth Avenue (3) 10.92 % July 2022 5.50 % 355,328 355,328 650 Fifth Avenue 50.00 % October 2022 4.95 % 225,000 — 21 East 66th Street 32.28 % April 2023 3.60 % 12,000 12,000 3 Columbus Circle 48.90 % March 2025 3.61 % 350,000 350,000 11 Madison Avenue 60.00 % September 2025 3.84 % 1,400,000 1,400,000 800 Third Avenue 60.52 % February 2026 3.37 % 177,000 177,000 400 East 57th Street 41.00 % November 2026 3.00 % 100,000 100,000 Stonehenge Portfolio (4) Various Various 4.17 % 359,095 362,518 1745 Broadway (5) — 340,000 Total fixed rate debt $ 3,448,423 $ 3,566,846 Floating Rate Debt: 55 West 46th Street (6) 25.00 % October 2017 3.52 % $ 165,328 $ 157,322 175-225 Third Street Brooklyn, New York 95.00 % December 2017 5.25 % 40,000 40,000 Jericho Plaza (7) 11.67 % March 2018 5.37 % 79,530 76,993 724 Fifth Avenue 50.00 % April 2018 3.64 % 275,000 275,000 1552 Broadway (8) 50.00 % April 2018 5.41 % 185,410 185,410 280 Park Avenue (9) 50.00 % September 2019 3.09 % 1,200,000 900,000 121 Greene Street 50.00 % November 2019 2.72 % 15,000 15,000 1745 Broadway (10) 56.87 % January 2020 3.07 % 345,000 — 10 East 53rd Street 55.00 % February 2020 3.47 % 170,000 125,000 131-137 Spring Street 20.00 % August 2020 2.77 % 141,000 141,000 11 West 34th Street 30.00 % January 2021 2.68 % 23,000 23,000 100 Park Avenue 49.90 % February 2021 2.97 % 360,000 360,000 One Vanderbilt (11) 71.01 % September 2021 4.72 % 271,229 — 605 West 42nd Street (12) 20.00 % August 2027 2.84 % 550,000 539,000 21 East 66th Street 32.28 % June 2033 3.62 % 1,667 1,726 Stonehenge Portfolio Various April 2018 2.47 % 55,340 65,577 650 Fifth Avenue (13) — 77,500 Total floating rate debt $ 3,877,504 $ 2,982,528 Total joint venture mortgages and other loans payable $ 7,325,927 $ 6,549,374 Deferred financing costs, net (127,318 ) (95,408 ) Total joint venture mortgages and other loans payable, net $ 7,198,609 $ 6,453,966 (1) Economic interest represent the Company's interests in the joint venture as of September 30, 2017 . Changes in ownership or economic interests, if any, within the current year are disclosed in the notes to the investment in unconsolidated joint ventures note above. (2) Effective weighted average interest rate for the three months ended September 30, 2017 , taking into account interest rate hedges in effect during the period. (3) These loans are comprised of a $300.0 million fixed rate mortgage loan and $355.3 million mezzanine loan. The mezzanine loan is subject to accretion based on the difference between contractual interest rate and contractual pay rate. (4) Amount is comprised of $34.0 million , $137.7 million , $172.5 million , and $14.9 million in fixed-rate mortgages that mature in November 2017, August 2019, June 2024, and February 2027, respectively. (5) In January 2017, this loan was refinanced with a floating rate loan as shown above. (6) This loan has a committed amount of $190.0 million , of which $24.7 million was unfunded as of September 30, 2017 . In October 2017, this loan was refinanced with a new $195.0 million mortgage loan with a floating interest rate of 213 basis points over 30-day LIBOR and a maturity date of November 2020. (7) The property secures a two year $100.0 million loan, of which $79.5 million is currently outstanding. (8) These loans are comprised of a $145.0 million mortgage loan and a $41.5 million mezzanine loan. As of September 30, 2017 , $0.6 million of the mortgage loan and $0.5 million of the mezzanine loan were unfunded. In October 2017, this loan was refinanced with a new $195.0 million mortgage loan with a floating interest rate of 265 basis points over 30-day LIBOR and a maturity date of October 2020. (9) In August 2017, this loan was refinanced with a new $1.075 billion mortgage loan and a new $125.0 million mezzanine loan, which carry floating interest rates of 148 basis points over 30-day LIBOR and 385 basis points over 30-day LIBOR, respectively. Both the mortgage loan and mezzanine loan initially mature in September 2019. (10) This loan has a committed amount of $375.0 million , of which $30.0 million was unfunded as of September 30, 2017 . (11) This loan is a $1.5 billion construction facility in connection with the development of One Vanderbilt. This facility bears interest at 350 basis points over 30-day LIBOR, with reduction based on meeting certain conditions, and has an initial five -year term with two one -year extension options. Advances under the loan are subject to incurred costs, funded equity, loan to value thresholds, and entering into construction contracts. (12) In August 2017, this loan was refinanced with a new $550.0 million mortgage note, with a floating interest rate of 144 basis points over 30-day LIBOR and a maturity date of August 2027. (13) In September 2017, this loan was refinanced with a fixed rate loan as shown above.
Schedule of combined balance sheets for the unconsolidated joint ventures	The combined balance sheets for the unconsolidated joint ventures, at September 30, 2017 and December 31, 2016 are as follows (in thousands): September 30, 2017 December 31, 2016 Assets Commercial real estate property, net $ 9,944,280 $ 9,131,717 Cash and restricted cash 370,596 328,455 Tenant and other receivables, related party receivables, and deferred rents receivable, net of allowance 267,244 232,778 Debt and preferred equity investments, net 201,731 336,164 Other assets 636,365 683,481 Total assets $ 11,420,216 $ 10,712,595 Liabilities and members' equity Mortgages and other loans payable, net $ 7,198,609 $ 6,453,966 Deferred revenue/gain 340,310 356,414 Other liabilities 411,261 391,500 Members' equity 3,470,036 3,510,715 Total liabilities and members' equity $ 11,420,216 $ 10,712,595 Company's investments in unconsolidated joint ventures $ 2,045,796 $ 1,890,186
Schedule of combined statements of income for the unconsolidated joint ventures	The combined statements of operations for the unconsolidated joint ventures, for the three and nine months ended September 30, 2017 and 2016 , are as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Total revenues $ 216,100 $ 184,221 $ 643,210 $ 498,308 Operating expenses 38,055 34,727 115,996 89,147 Ground rent 4,182 3,744 12,612 10,670 Real estate taxes 37,282 30,814 107,391 79,356 Interest expense, net of interest income 61,066 51,789 176,096 147,876 Amortization of deferred financing costs 4,030 7,155 17,994 17,667 Transaction related costs — 5,359 146 5,359 Depreciation and amortization 61,447 56,890 198,556 132,035 Total expenses 206,062 190,478 628,791 482,110 Loss on early extinguishment of debt (7,638 ) — (7,638 ) (1,606 ) Net income (loss) before gain on sale $ 2,400 $ (6,257 ) $ 6,781 $ 14,592 Company's equity in net income (loss) from unconsolidated joint ventures $ 4,078 $ (3,968 ) $ 14,104 $ 11,969

Deferred Costs (Tables)

Deferred Costs (Tables)	9 Months Ended
	Sep. 30, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of components of deferred costs	Deferred costs at September 30, 2017 and December 31, 2016 consisted of the following (in thousands): September 30, 2017 December 31, 2016 Deferred leasing costs $ 464,788 $ 468,971 Less: accumulated amortization (216,807 ) (201,371 ) Deferred costs, net $ 247,981 $ 267,600

Mortgages and Other Loans Pay39

Mortgages and Other Loans Payable (Tables)	9 Months Ended
	Sep. 30, 2017
Mortgages and Other Loans Payable
Schedule of first mortgages and other loans payable collateralized by the respective properties and assignment of leases	The first mortgages and other loans payable collateralized by the respective properties and assignment of leases or debt investments at September 30, 2017 and December 31, 2016 , respectively, were as follows (amounts in thousands): Property Maturity Date Interest Rate (1) September 30, 2017 December 31, 2016 Fixed Rate Debt: Unsecured Loan June 2018 4.81 % $ 16,000 $ 16,000 One Madison Avenue May 2020 5.91 % 494,264 517,806 762 Madison Avenue February 2022 5.00 % 771 7,694 100 Church Street July 2022 4.68 % 218,237 221,446 919 Third Avenue (2) June 2023 5.12 % 500,000 500,000 420 Lexington Avenue October 2024 3.99 % 300,000 300,000 1515 Broadway March 2025 3.93 % 876,613 888,531 400 East 58th Street (3) November 2026 3.00 % 40,000 40,000 Landmark Square January 2027 4.90 % 100,000 100,000 485 Lexington Avenue February 2027 4.25 % 450,000 450,000 1080 Amsterdam (4) February 2027 3.58 % 36,363 — 315 West 33rd Street February 2027 4.17 % 250,000 — Series J Preferred Units (5) April 2051 3.75 % 4,000 4,000 885 Third Avenue (6) — 267,650 FHLBNY Facility (7) — 105,000 FHLBNY Facility (7) — 100,000 Total fixed rate debt $ 3,286,248 $ 3,518,127 Floating Rate Debt: 719 Seventh Avenue February 2018 4.27 % $ 41,171 $ 37,388 183, 187 Broadway & 5-7 Dey Street May 2018 3.92 % 58,000 58,000 2016 Master Repurchase Agreement July 2018 3.73 % 184,642 184,642 220 East 42nd Street October 2020 2.82 % 275,000 275,000 One Vanderbilt Avenue (8) — 64,030 1080 Amsterdam (9) — 3,525 Total floating rate debt $ 558,813 $ 622,585 Total fixed rate and floating rate debt $ 3,845,061 $ 4,140,712 Mortgages reclassed to liabilities related to assets held for sale — — Total mortgages and other loans payable $ 3,845,061 $ 4,140,712 Deferred financing costs, net of amortization (40,887 ) (66,882 ) Total mortgages and other loans payable, net $ 3,804,174 $ 4,073,830 (1) Effective weighted average interest rate for the quarter ended September 30, 2017 , taking into account interest rate hedges in effect during the period. (2) We own a 51.0% controlling interest in the consolidated joint venture that is the borrower on this loan. (3) The loan carries a fixed interest rate of 3.00% for the first 5 years and is prepayable without penalty in year 5 . (4) The loan is comprised of a $35.5 million mortgage loan and $0.9 million subordinate loan with a fixed interest rate of 3.50% and 7.00% , respectively, for the first 5 years and is prepayable without penalty in year 5 . (5) In connection with the acquisition of a commercial real estate property, the Operating Partnership issued $4.0 million , 3.75% Series J Preferred Units of limited partnership interest, or the Series J Preferred Units, with a mandatory liquidation preference of $1,000 per unit. The Series J Preferred Units are accounted for as debt because they can be redeemed in cash by the Operating Partnership on the earlier of (i) the date of the sale of the property or (ii) April 30, 2051 or at the option of the unitholders as provided for in the related agreement. (6) In February 2016, we closed on the sale of 885 Third Avenue. The sale did not meet the criteria for sale accounting at that time. In April 2017, the mortgage was refinanced by the buyer, resulting in the Company deconsolidating the property from its financial statements in the second quarter of 2017. (7) The facility was repaid in January 2017. (8) In September 2016, we closed on a $1.5 billion construction facility in connection with the development of One Vanderbilt Avenue. In January 2017, we admitted two partners, National Pension Service of Korea and Hines Interest LP, into the One Vanderbilt Avenue development project. In April 2017, the criteria for deconsolidation were met, and the development is shown within investments in unconsolidated joint ventures. See Note 6, "Investments in Unconsolidated Joint Ventures". (9) In January 2017, this loan was refinanced with a fixed rate loan as shown above.

Corporate Indebtedness (Tables)

Corporate Indebtedness (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 and December 31, 2016 , respectively, by scheduled maturity date (dollars in thousands): Issuance September 30, September 30, December 31, Coupon Rate (1) Effective Rate Initial Term (in Years) Maturity Date October 12, 2010 (2) $ 269,000 $ 268,628 $ 334,077 3.00 % 3.00 % 7 October 2017 August 5, 2011 (3) 250,000 249,934 249,880 5.00 % 5.00 % 7 August 2018 March 16, 2010 (3) 250,000 250,000 250,000 7.75 % 7.75 % 10 March 2020 November 15, 2012 (3) 200,000 200,000 200,000 4.50 % 4.50 % 10 December 2022 December 17, 2015 (3) 100,000 100,000 100,000 4.27 % 4.27 % 10 December 2025 $ 1,069,000 $ 1,068,562 $ 1,133,957 Deferred financing costs, net (4,018 ) (5,642 ) $ 1,069,000 $ 1,064,544 $ 1,128,315 (1) Interest on the senior unsecured notes is payable semi-annually with principal and unpaid interest due on the scheduled maturity dates. (2) Issued by the Operating Partnership. The notes were senior unsecured obligations of the Operating Partnership and exchangeable at a calculated exchange rate upon the occurrence of specified events and during the period beginning on the twenty-second scheduled trading day prior to the maturity date and ending on the second business day prior to the maturity date, into cash, or a combination of cash and shares of SL Green's common stock, if any, at our option. In accordance with the terms of the indenture, the notes became exchangeable commencing September 14, 2017 and the Operating Partnership elected to settle exchanges in cash. In October 2017, all note holders elected to exchange the notes and the notes were repaid for $350.8 million , excluding accrued interest based on the applicable exchange rate. (3) Issued by the Company, the Operating Partnership and ROP, as co-obligors. In October 2017, the Company, the Operating Partnership and ROP, as co-obligors issued an additional $100.0 million of the 4.50% senior unsecured bonds due December 2022. The additional notes priced at 105.334% plus accrued interest from June 1, 2017, with a yield to maturity of 3.298% .
Schedule of combined aggregate principal maturities	Combined aggregate principal maturities of mortgages and other loans payable, 2012 credit facility, trust preferred securities, senior unsecured notes and our share of joint venture debt as of September 30, 2017 , including as-of-right extension options and put options, were as follows (in thousands): Scheduled Amortization Principal Revolving Credit Facility Unsecured Term Loan Trust Preferred Securities Senior Unsecured Notes Total Joint Venture Debt Remaining 2017 $ 12,846 $ — $ — $ — $ — $ 269,000 (1) $ 281,846 $ 79,787 2018 54,937 299,813 — — — 250,000 604,750 242,799 2019 59,618 — — 1,183,000 — — 1,242,618 705,574 2020 41,427 679,531 280,000 — — 250,000 1,250,958 320,914 2021 30,418 — — — — — 30,418 376,765 Thereafter 90,532 2,575,939 — — 100,000 300,000 3,066,471 1,465,371 $ 289,778 $ 3,555,283 $ 280,000 $ 1,183,000 $ 100,000 $ 1,069,000 $ 6,477,061 $ 3,191,210
Schedule of consolidated interest expense, excluding capitalized interest	Consolidated interest expense, excluding capitalized interest, was comprised of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Interest expense before capitalized interest $ 72,859 $ 78,715 $ 217,273 $ 276,437 Interest capitalized (6,869 ) (6,084 ) (19,892 ) (18,135 ) Interest income (356 ) (66 ) (1,269 ) (1,976 ) Interest expense, net $ 65,634 $ 72,565 $ 196,112 $ 256,326

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2017
Related Party Transactions [Abstract]
Schedule of amounts due from/to related parties	Amounts due from joint ventures and related parties at September 30, 2017 and December 31, 2016 consisted of the following (in thousands): September 30, 2017 December 31, 2016 Due from joint ventures $ 16,736 $ 1,240 Other 7,332 14,616 Related party receivables $ 24,068 $ 15,856

Noncontrolling Interests on t42

Noncontrolling Interests on the Company's Consolidated Financial Statements (Tables)	9 Months Ended
	Sep. 30, 2017
Noncontrolling Interest [Abstract]
Schedule of Noncontrolling Interest	Below is the rollforward analysis of the activity relating to the noncontrolling interests in the Operating Partnership as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Balance at beginning of period $ 473,882 $ 424,206 Distributions (10,639 ) (12,671 ) Issuance of common units 23,273 78,495 Redemption of common units (15,353 ) (31,805 ) Net income 2,707 10,136 Accumulated other comprehensive income allocation (303 ) 1,299 Fair value adjustment (2,669 ) 4,222 Balance at end of period $ 470,898 $ 473,882
Schedule of Preferred Unit Activity	Below is the rollforward analysis of the activity relating to the preferred units in the Operating Partnership as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Balance at beginning of period $ 302,010 $ 282,516 Issuance of preferred units — 22,793 Redemption of preferred units (125 ) (3,299 ) Balance at end of period $ 301,885 $ 302,010

Stockholders' Equity of the C43

Stockholders' Equity of the Company (Tables)	9 Months Ended
	Sep. 30, 2017
Stockholders' Equity Note [Abstract]
Class of Treasury Stock	In August 2016, our board of directors approved a stock repurchase plan under which we can buy up to $1.0 billion of shares of our common stock. At September 30, 2017 , repurchases made under the stock repurchase plans were as follows: Period Total number of shares purchased Average price paid per share Total number of shares purchased as part of the repurchase plan or programs Maximum approximate dollar value of shares that may yet be purchased under the plan (in millions) First quarter 2017 982 $103.89 982 $999.9 Second quarter 2017 2,447,153 $103.41 2,448,135 $746.8 Third quarter 2017 951,866 $101.67 3,400,001 $650.0
Schedule of Earnings Per Share	SL Green's earnings per share for the three and nine months ended September 30, 2017 and 2016 are computed as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Numerator 2017 2016 2017 2016 Basic Earnings: Income attributable to SL Green common stockholders $ 38,869 $ 34,252 $ 58,442 $ 190,930 Effect of Dilutive Securities: Redemption of units to common shares 1,812 1,663 2,707 8,171 Diluted Earnings: Income attributable to SL Green common stockholders $ 40,681 $ 35,915 $ 61,149 $ 199,101 Three Months Ended September 30, Nine Months Ended September 30, Denominator 2017 2016 2017 2016 Basic Shares: Weighted average common stock outstanding 97,783 100,233 99,431 100,140 Effect of Dilutive Securities: Operating Partnership units redeemable for common shares 4,543 4,497 4,570 4,272 Stock-based compensation plans 244 413 279 349 Diluted weighted average common stock outstanding 102,570 105,143 104,280 104,761

Partners' Capital of the Oper44

Partners' Capital of the Operating Partnership (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Schedule of calculation of numerator and denominator in earnings per unit	The Operating Partnership's earnings per unit for the three and nine months ended September 30, 2017 and 2016, respectively are computed as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Numerator 2017 2016 2017 2016 Basic and Diluted Earnings: Net income attributable to SLGOP common unitholders $ 40,681 $ 35,915 $ 61,149 $ 199,101 Three Months Ended September 30, Nine Months Ended September 30, Denominator 2017 2016 2017 2016 Basic units: Weighted average common units outstanding 102,326 104,730 104,001 104,412 Effect of Dilutive Securities: Stock-based compensation plans 244 413 279 349 Diluted weighted average common units outstanding 102,570 105,143 104,280 104,761

Share-based Compensation (Table

Share-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of weighted average assumptions used to estimate the grant date fair value of options granted	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 with the following weighted average assumptions for grants during the nine months ended September 30, 2017 and the year ended December 31, 2016 . September 30, 2017 December 31, 2016 Dividend yield 2.50 % 2.37 % Expected life 4.4 years 3.7 years Risk-free interest rate 1.73 % 1.57 % Expected stock price volatility 28.21 % 26.76 %
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 September 30, 2017 and December 31, 2016 , and changes during the nine months ended September 30, 2017 and year ended December 31, 2016 are as follows: September 30, 2017 December 31, 2016 Options Outstanding Weighted Average Exercise Price Options Outstanding Weighted Average Exercise Price Balance at beginning of period $ 1,737,213 $ 98.44 $ 1,595,007 $ 95.52 Granted 171,000 105.70 445,100 105.86 Exercised (146,277 ) 84.02 (192,875 ) 76.90 Lapsed or cancelled (65,300 ) 122.30 (110,019 ) 123.86 Balance at end of period $ 1,696,636 $ 99.50 $ 1,737,213 $ 98.44 Options exercisable at end of period 939,485 $ 91.71 748,617 $ 87.72 Weighted average fair value of options granted during the period $ 3,775,639 $ 8,363,036
Summary of restricted stock and charges during the period	A summary of the Company's restricted stock as of September 30, 2017 and December 31, 2016 and charges during the nine months ended September 30, 2017 and the year ended December 31, 2016 , are as follows: September 30, 2017 December 31, 2016 Balance at beginning of period 3,202,031 3,137,881 Granted 300 98,800 Cancelled — (34,650 ) Balance at end of period 3,202,331 3,202,031 Vested during the period 86,736 83,822 Compensation expense recorded $ 7,277,054 $ 7,153,966 Weighted average fair value of restricted stock granted during the period $ 30,813 $ 10,650,077

Accumulated Other Comprehensi46

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2017
SL Green Realty Corp
Accumulated Other Comprehensive Income (Loss) [Line Items]
Schedule of accumulated other comprehensive income (loss)	The following tables set forth the changes in accumulated other comprehensive income (loss) by component as of September 30, 2017 (in thousands): Net unrealized gain on derivative instruments ( 1 ) SL Green’s share of joint venture net unrealized gain on derivative instruments ( 2 ) Net unrealized gain on marketable securities Total Balance at December 31, 2016 $ 12,596 $ 4,021 $ 5,520 $ 22,137 Other comprehensive (loss) before reclassifications (4,669 ) (947 ) (1,133 ) (6,749 ) Amounts reclassified from accumulated other comprehensive income 1,336 591 (3,130 ) (1,203 ) Balance at September 30, 2017 $ 9,263 $ 3,665 $ 1,257 $ 14,185 (1) Amount reclassified from accumulated other comprehensive income (loss) is included in interest expense in the respective consolidated statements of operations. As of September 30, 2017 and December 31, 2016 , the deferred net losses from these terminated hedges, which is included in accumulated other comprehensive loss relating to net unrealized loss on derivative instrument, was $3.7 million and $7.1 million , respectively. (2) Amount reclassified from accumulated other comprehensive income (loss) is included in equity in net income from unconsolidated joint ventures in the respective consolidated statements of operations.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 Total Level 1 Level 2 Level 3 Assets: Marketable securities $ 28,802 $ — $ 28,802 $ — Interest rate cap and swap agreements (included in other assets) $ 13,727 $ — $ 13,727 $ — December 31, 2016 Total Level 1 Level 2 Level 3 Assets: Marketable securities $ 85,110 $ 48,315 $ 36,795 $ — Interest rate cap and swap agreements (included in other assets) $ 21,090 $ — $ 21,090 $ — Liabilities: Interest rate cap and swap agreements (included in accrued interest payable and other liabilities) $ 1 $ — $ 1 $ —
Fair value, by balance sheet grouping	The following table provides the carrying value and fair value of these financial instruments as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Carrying Value (1) Fair Value Carrying Value (1) Fair Value Debt and preferred equity investments $ 2,020,739 (2) $ 1,640,412 (2) Fixed rate debt $ 5,154,810 $ 5,398,870 $ 5,452,084 $ 5,722,494 Variable rate debt 1,321,813 1,314,223 1,105,585 1,110,110 $ 6,476,623 $ 6,713,093 $ 6,557,669 $ 6,832,604 (1) Amounts exclude net deferred financing costs. (2) At September 30, 2017 , debt and preferred equity investments had an estimated fair value ranging between $2.0 billion and $2.2 billion . At December 31, 2016 , debt and preferred equity investments had an estimated fair value ranging between $1.6 billion and $1.8 billion .

Financial Instruments_ Deriva48

Financial Instruments: Derivatives and Hedging (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 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 (amounts in thousands). Notional Value Strike Rate Effective Date Expiration Date Balance Sheet Location Fair Value Interest Rate Swap $ 200,000 0.938 % October 2014 December 2017 Other Assets $ 105 Interest Rate Swap 150,000 0.940 % October 2014 December 2017 Other Assets 78 Interest Rate Swap 150,000 0.940 % October 2014 December 2017 Other Assets 78 Interest Rate Cap 137,500 4.000 % September 2017 September 2019 Other Assets 4 Interest Rate Swap 200,000 1.131 % July 2016 July 2023 Other Assets 8,998 Interest Rate Swap 100,000 1.161 % July 2016 July 2023 Other Assets 4,335 Interest Rate Swap 100,000 2.287 % November 2017 November 2027 Other Assets 129 $ 13,727
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 September 30, 2017 and 2016 , respectively (in thousands): Amount of (Loss) Location of (Loss) Reclassified from Accumulated Other Comprehensive Loss into Income Amount of Loss Location of (Loss) Recognized in Income on Derivative Amount of (Loss) Gain Three Months Ended September 30, Three Months Ended September 30, Three Months Ended September 30, Derivative 2017 2016 2017 2016 2017 2016 Interest Rate Swaps/Caps $ (304 ) $ (7 ) Interest expense $ 85 $ 1,442 Interest expense $ 4 $ — Share of unconsolidated joint ventures' derivative instruments (290 ) (222 ) Equity in net income from unconsolidated joint ventures 185 547 Equity in net income from unconsolidated joint ventures (48 ) 830 $ (594 ) $ (229 ) $ 270 $ 1,989 $ (44 ) $ 830 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 nine months ended September 30, 2017 and 2016 , respectively (in thousands): Amount of (Loss) Recognized in Location of (Loss) Reclassified from Accumulated Other Comprehensive Loss into Income Amount of Loss Location of (Loss) Recognized in Income on Derivative Amount of (Loss) Nine Months Ended September 30, Nine Months Ended September 30, Nine Months Ended September 30, Derivative 2017 2016 2017 2016 2017 2016 Interest Rate Swaps/Caps $ (5,477 ) $ (8,112 ) Interest expense $ 1,583 $ 8,073 Interest expense $ (4 ) $ (38 ) Share of unconsolidated joint ventures' derivative instruments (1,277 ) (5,992 ) Equity in net income from unconsolidated joint ventures 876 1,465 Equity in net income from unconsolidated joint ventures (109 ) (206 ) $ (6,754 ) $ (14,104 ) $ 2,459 $ 9,538 $ (113 ) $ (244 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum rental payments for operating leases	The following is a schedule of future minimum lease payments under capital leases and non-cancellable operating leases with initial terms in excess of one year as of September 30, 2017 (in thousands): Capital lease Non-cancellable operating leases Remaining 2017 $ 597 $ 7,763 2018 2,387 31,049 2019 2,411 31,066 2020 2,620 31,436 2021 2,794 31,628 Thereafter 822,688 732,724 Total minimum lease payments $ 833,497 $ 865,666 Amount representing interest (790,837 ) Capital lease obligations $ 42,660
Schedule of future minimum rental payments for capital leases	The following is a schedule of future minimum lease payments under capital leases and non-cancellable operating leases with initial terms in excess of one year as of September 30, 2017 (in thousands): Capital lease Non-cancellable operating leases Remaining 2017 $ 597 $ 7,763 2018 2,387 31,049 2019 2,411 31,066 2020 2,620 31,436 2021 2,794 31,628 Thereafter 822,688 732,724 Total minimum lease payments $ 833,497 $ 865,666 Amount representing interest (790,837 ) Capital lease obligations $ 42,660

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Schedule of selected results of operations and selected asset information	Selected consolidated results of operations for the three and nine months ended September 30, 2017 and 2016 , and selected asset information as of September 30, 2017 and December 31, 2016 , regarding our operating segments are as follows (in thousands): Real Estate Segment Debt and Preferred Equity Segment Total Company Total revenues Three months ended: September 30, 2017 $ 326,780 $ 47,820 $ 374,600 September 30, 2016 341,285 75,396 416,681 Nine months ended: September 30, 2017 1,001,390 148,741 1,150,131 September 30, 2016 1,315,392 174,347 1,489,739 Net income (loss) before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain on sale of real estate, net, depreciable real estate reserves, and gain on sale of investment in marketable securities Three months ended: September 30, 2017 $ 4,873 $ 39,892 $ 44,765 September 30, 2016 (32,731 ) 75,452 42,721 Nine months ended: September 30, 2017 (504 ) 132,402 131,898 September 30, 2016 (187,222 ) 168,295 (18,927 ) Total assets As of: September 30, 2017 $ 12,939,363 $ 2,170,507 $ 15,109,870 December 31, 2016 13,868,672 1,989,115 15,857,787
Schedule of reconciliation of income from continuing operations to net income attributable to SL Green common stockholders	The table below reconciles income from continuing operations to net income for the three and nine months ended September 30, 2017 and 2016 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Net income (loss) before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain on sale of real estate, net, depreciable real estate reserves, and gain on sale of investment in marketable securities $ 44,765 $ 42,721 $ 131,898 $ (18,927 ) Equity in net gain on sale of interest in unconsolidated joint venture/real estate 1,030 225 16,166 43,588 Gain (loss) on sale of real estate, net — 397 (3,256 ) 210,750 Depreciable real estate reserves — — (85,336 ) (10,387 ) Gain (loss) on sale of investment in marketable securities — — 3,262 (83 ) Net income $ 45,795 $ 43,343 $ 62,734 $ 224,941

Organization and Basis of Pre51

Organization and Basis of Presentation - Additional Information (Details) - SL Green Operating Partnership	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Organization
Percentage of ownership in SL Green Management LLC owned by operating partnership (percent)	100.00%
Noncontrolling interest in the operating partnership (as a percent)	4.45%	4.16%

Organization and Basis of Pre52

Organization and Basis of Presentation - Schedule of Commercial Office Properties (Details) $ in Billions	9 Months Ended
	Sep. 30, 2017USD ($)ft²buildingshares
Real estate properties
Number of Properties | building	99
Approximate Square Feet unaudited (sqft)	31,800,088
Weighted Average Occupancy unaudited (as a percent)	90.40%
Debt and preferred equity investments including investments held by unconsolidated joint ventures | $	$ 2.2
Debt and preferred equity investments and other financing receivables included in other balance sheet items | $	$ 0.1
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 Properties | building	84
Approximate Square Feet unaudited (sqft)	28,671,127
Weighted Average Occupancy unaudited (as a percent)	90.80%
Residential
Real estate properties
Number of Properties | building	15
Approximate Square Feet unaudited (sqft)	3,128,961
Weighted Average Occupancy unaudited (as a percent)	86.40%
Managed office properties
Real estate properties
Approximate Square Feet unaudited (sqft)	336,000
Consolidated properties
Real estate properties
Number of Properties | building	63
Approximate Square Feet unaudited (sqft)	20,826,609
Consolidated properties | Commercial properties
Real estate properties
Number of Properties | building	60
Approximate Square Feet unaudited (sqft)	20,354,504
Consolidated properties | Residential
Real estate properties
Number of Properties | building	3
Approximate Square Feet unaudited (sqft)	472,105
Unconsolidated properties
Real estate properties
Number of Properties | building	36
Approximate Square Feet unaudited (sqft)	10,973,479
Unconsolidated properties | Commercial properties
Real estate properties
Number of Properties | building	24
Approximate Square Feet unaudited (sqft)	8,316,623
Unconsolidated properties | Residential
Real estate properties
Number of Properties | building	12
Approximate Square Feet unaudited (sqft)	2,656,856
Manhattan
Real estate properties
Number of Properties | building	57
Approximate Square Feet unaudited (sqft)	24,369,327
Weighted Average Occupancy unaudited (as a percent)	92.20%
Manhattan | Office
Real estate properties
Number of Properties | building	31
Approximate Square Feet unaudited (sqft)	22,612,745
Weighted Average Occupancy unaudited (as a percent)	93.40%
Manhattan | Retail
Real estate properties
Number of Properties | building	13
Approximate Square Feet unaudited (sqft)	650,553
Weighted Average Occupancy unaudited (as a percent)	94.50%
Manhattan | Development/Redevelopment
Real estate properties
Number of Properties | building	11
Approximate Square Feet unaudited (sqft)	929,499
Weighted Average Occupancy unaudited (as a percent)	59.90%
Manhattan | Fee Interest
Real estate properties
Number of Properties | building	2
Approximate Square Feet unaudited (sqft)	176,530
Weighted Average Occupancy unaudited (as a percent)	100.00%
Manhattan | Residential
Real estate properties
Number of Properties | building	15
Approximate Square Feet unaudited (sqft)	3,128,961
Weighted Average Occupancy unaudited (as a percent)	86.40%
Manhattan | Consolidated properties
Real estate properties
Number of Properties | building	36
Approximate Square Feet unaudited (sqft)	16,692,704
Manhattan | Consolidated properties | Office
Real estate properties
Number of Properties | building	24
Approximate Square Feet unaudited (sqft)	16,054,606
Manhattan | Consolidated properties | Retail
Real estate properties
Number of Properties | building	4
Approximate Square Feet unaudited (sqft)	302,583
Manhattan | Consolidated properties | Development/Redevelopment
Real estate properties
Number of Properties | building	7
Approximate Square Feet unaudited (sqft)	158,985
Manhattan | Consolidated properties | Fee Interest
Real estate properties
Number of Properties | building	1
Approximate Square Feet unaudited (sqft)	176,530
Manhattan | Consolidated properties | Residential
Real estate properties
Number of Properties | building	3
Approximate Square Feet unaudited (sqft)	472,105
Manhattan | Consolidated properties | Dual property type, retail portion
Real estate properties
Approximate Square Feet unaudited (sqft)	270,132
Manhattan | Consolidated properties | Dual property type, residential portion
Real estate properties
Approximate Square Feet unaudited (sqft)	222,855
Manhattan | Unconsolidated properties
Real estate properties
Number of Properties | building	21
Approximate Square Feet unaudited (sqft)	7,676,623
Manhattan | Unconsolidated properties | Office
Real estate properties
Number of Properties | building	7
Approximate Square Feet unaudited (sqft)	6,558,139
Manhattan | Unconsolidated properties | Retail
Real estate properties
Number of Properties | building	9
Approximate Square Feet unaudited (sqft)	347,970
Manhattan | Unconsolidated properties | Development/Redevelopment
Real estate properties
Number of Properties | building	4
Approximate Square Feet unaudited (sqft)	770,514
Manhattan | Unconsolidated properties | Fee Interest
Real estate properties
Number of Properties | building	1
Approximate Square Feet unaudited (sqft)	0
Manhattan | Unconsolidated properties | Residential
Real estate properties
Number of Properties | building	12
Approximate Square Feet unaudited (sqft)	2,656,856
Suburban
Real estate properties
Number of Properties | building	27
Approximate Square Feet unaudited (sqft)	4,301,800
Weighted Average Occupancy unaudited (as a percent)	83.30%
Suburban | Office
Real estate properties
Number of Properties | building	24
Approximate Square Feet unaudited (sqft)	4,248,800
Weighted Average Occupancy unaudited (as a percent)	83.10%
Suburban | Retail
Real estate properties
Number of Properties | building	1
Approximate Square Feet unaudited (sqft)	52,000
Weighted Average Occupancy unaudited (as a percent)	100.00%
Suburban | Development/Redevelopment
Real estate properties
Number of Properties | building	2
Approximate Square Feet unaudited (sqft)	1,000
Weighted Average Occupancy unaudited (as a percent)	100.00%
Suburban | Residential
Real estate properties
Number of Properties | building	0
Approximate Square Feet unaudited (sqft)	0
Weighted Average Occupancy unaudited (as a percent)	0.00%
Suburban | Consolidated properties
Real estate properties
Number of Properties | building	24
Approximate Square Feet unaudited (sqft)	3,661,800
Suburban | Consolidated properties | Office
Real estate properties
Number of Properties | building	22
Approximate Square Feet unaudited (sqft)	3,608,800
Suburban | Consolidated properties | Retail
Real estate properties
Number of Properties | building	1
Approximate Square Feet unaudited (sqft)	52,000
Suburban | Consolidated properties | Development/Redevelopment
Real estate properties
Number of Properties | building	1
Approximate Square Feet unaudited (sqft)	1,000
Suburban | Consolidated properties | Residential
Real estate properties
Number of Properties | building	0
Approximate Square Feet unaudited (sqft)	0
Suburban | Unconsolidated properties
Real estate properties
Number of Properties | building	3
Approximate Square Feet unaudited (sqft)	640,000
Suburban | Unconsolidated properties | Office
Real estate properties
Number of Properties | building	2
Approximate Square Feet unaudited (sqft)	640,000
Suburban | Unconsolidated properties | Retail
Real estate properties
Number of Properties | building	0
Approximate Square Feet unaudited (sqft)	0
Suburban | Unconsolidated properties | Development/Redevelopment
Real estate properties
Number of Properties | building	1
Approximate Square Feet unaudited (sqft)	0
Suburban | Unconsolidated properties | Residential
Real estate properties
Number of Properties | building	0
Approximate Square Feet unaudited (sqft)	0

Significant Accounting Polici53

Significant Accounting Policies - Investments in Commercial Real Estate Properties (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Investment in Commercial Real Estate Properties
Depreciable real estate reserves	$ 0	$ 0	$ (85,336,000)	$ (10,387,000)
Rental revenue from amortization of acquired leases	4,600,000	200,000	15,800,000	191,400,000
Reduction in interest expense from amortization of above-market rate mortgages	0	700,000	800,000	2,000,000
Identified intangible assets (included in other assets):
Gross amount	474,493,000		474,493,000		$ 651,099,000
Accumulated amortization	(398,047,000)		(398,047,000)		(410,930,000)
Net	76,446,000		76,446,000		240,169,000
Identified intangible liabilities (included in deferred revenue):
Gross amount	639,511,000		639,511,000		655,930,000
Accumulated amortization	(474,365,000)		(474,365,000)		(464,749,000)
Net	165,146,000		165,146,000		191,181,000
Net intangible assets reclassed to assets held for sale	3,900,000		3,900,000		0
Net intangible liabilities reclassed to liabilities relates to assets held for sale	1,100,000		$ 1,100,000		$ 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)			14 years
Maximum | Below-market leases
Investment in Commercial Real Estate Properties
Estimated useful life of other intangible assets (in years)			14 years
Maximum | In-place leases
Investment in Commercial Real Estate Properties
Estimated useful life of other intangible assets (in years)			14 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
388-390 Greenwich Street
Investment in Commercial Real Estate Properties
Amortization of below market lease		$ 0		$ 172,400,000
125 Chubb Avenue and Stamford Towers
Investment in Commercial Real Estate Properties
Depreciable real estate reserves	$ 0		$ 85,300,000

Significant Accounting Polici54

Significant Accounting Policies - Investment in Marketable Securities (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Investment in Marketable Securities
Marketable securities	$ 28,802,000		$ 28,802,000		$ 85,110,000
Cost basis	27,500,000		27,500,000		36,000,000
Proceeds from sale of marketable securities	800,000	$ 1,700,000	55,200,000	$ 6,900,000
Fair Value
Investment in Marketable Securities
Marketable securities	28,802,000		28,802,000		85,110,000
Equity marketable securities
Investment in Marketable Securities
Marketable securities	0		0		48,315,000
Cost basis	0		0		43,300,000
Commercial mortgage-backed securities
Investment in Marketable Securities
Marketable securities	$ 28,802,000		$ 28,802,000		$ 36,795,000

Significant Accounting Polici55

Significant Accounting Policies - Revenue Recognition/Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Income taxes
Federal, state and local tax provision	$ 0.1	$ 2.8

Significant Accounting Polici56

Significant Accounting Policies - Concentrations of Credit Risk/Accounting Standards Updates (Details) - Annualized rent - Customer concentration	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017Tenant
Concentration of Credit Risk
Number of tenants (tenants)		2
Maximum percentage of annualized rent for any one tenant not individually disclosed (percent) (more than)	5.00%	5.00%
1515 Broadway
Concentration of Credit Risk
Percentage of concentration (percent)	8.90%
11 Madison Avenue
Concentration of Credit Risk
Percentage of concentration (percent)	6.30%
1185 Avenue of the Americas
Concentration of Credit Risk
Percentage of concentration (percent)	6.20%
420 Lexington Avenue
Concentration of Credit Risk
Percentage of concentration (percent)	5.40%
Tenant 1
Concentration of Credit Risk
Percentage of concentration (percent)		8.80%
Tenant 2
Concentration of Credit Risk
Percentage of concentration (percent)		6.70%

Properties Held for Sale and 57

Properties Held for Sale and Property Dispositions (Details) $ in Millions	1 Months Ended				9 Months Ended
	Sep. 30, 2017ft²	Jul. 31, 2017USD ($)ft²	Apr. 30, 2017USD ($)ft²	Feb. 29, 2016USD ($)ft²	Sep. 30, 2017USD ($)ft²	Oct. 31, 2017USD ($)
Properties Sold [Abstract]
Approximate Square Feet | ft²	31,800,088				31,800,088
885 Third Avenue
Properties Sold [Abstract]
Approximate Square Feet | ft²				607,000
Sales Price				$ 453
Gain on Sale (Loss)				$ (8.8)
520 White Plains Road
Properties Sold [Abstract]
Approximate Square Feet | ft²			180,000
Sales Price			$ 21
Gain on Sale (Loss)			$ (14.6)
102 Greene Street
Properties Sold [Abstract]
Approximate Square Feet | ft²			9,200
Sales Price			$ 43.5
Gain on Sale (Loss)			$ 4.9
Employee compensation award					$ 0.9
Joint venture, ownership percentage sold	10.00%		90.00%
680/750 Washington Boulevard
Properties Sold [Abstract]
Approximate Square Feet | ft²		325,000
Sales Price		$ 97
Gain on Sale (Loss)		$ (44.2)
Subsequent Event | 16 Court
Properties Sold [Abstract]
Sales Price						$ 171

Debt and Preferred Equity Inv58

Debt and Preferred Equity Investments - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Feb. 28, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2014
Mortgage Loans on Real Estate [Line Items]
Aggregate weighted average current yield (as a percent)	9.49%
Debt Investments Held [Abstract]
Carrying Value	$ 2,020,739,000		$ 1,640,412,000
Mezzanine/Jr. Mortgage Loan with an Initial Maturity Date of April 2017
Debt Investments Held [Abstract]
Carrying Value	250,200,000		0	$ 0
Mezzanine Loan with an Initial Maturity Date of March 2020
Debt Investments Held [Abstract]
Amount participated out	1,200,000
Mezzanine Loan, with an Initial Maturity Date of June 2024
Debt Investments Held [Abstract]
Amount participated out	12,000,000
Mezzanine Loan with an Initial Maturity Date of December 2017
Debt Investments Held [Abstract]
Amount participated out	14,600,000
Mezzanine Loan with an Initial Maturity Date of December 2017, 2
Debt Investments Held [Abstract]
Amount participated out	14,100,000
Mortgage Mezzanine Loan with an Initial Maturity Date of December 2017
Debt Investments Held [Abstract]
Amount participated out	5,100,000
Mortgage/Mezzanine Loan with an Initial Maturity Date of January 2019
Debt Investments Held [Abstract]
Amount participated out	21,200,000
Debt Investments in Mortgage Loans
Debt Investments Held [Abstract]
Future Funding Obligations	181,320,000
Senior Financing	7,115,310,000
Carrying Value	1,876,759,000		1,592,537,000
Total fixed rate
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	3,617,095,000
Carrying Value	632,834,000		360,359,000
Total fixed rate | Mezzanine/Jr. Mortgage Loan with an Initial Maturity Date of April 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	250,164,000		0
Loan acquired	259,300,000
Total fixed rate | Mortgage Loan, February 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	26,352,000		26,311,000
Loan acquired					$ 26,400,000
Discount amount					200,000
Total fixed rate | Mortgage Loan, August 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	275,000		380,000
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of March 2020
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	1,160,000,000
Carrying Value	201,757,000		0
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 | Mezzanine Loan with an Initial Maturity Date of April 2022
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	147,000,000
Carrying Value	24,909,000		0
Total fixed rate | Mezzanine Loan, November 2023
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	87,595,000
Carrying Value	12,697,000		12,692,000
Total fixed rate | Mezzanine Loan, with an Initial Maturity Date of June 2024
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	115,000,000
Carrying Value	12,930,000		12,925,000
Total fixed rate | Mezzanine Loan, 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 November 2026
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	340,000,000
Carrying Value	15,000,000		15,000,000
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of June 2027
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	1,657,500,000
Carrying Value	55,250,000		0
Total fixed rate | Mezzanine Loan, June 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0		66,129,000
Total fixed rate | Junior Mortgage Participation/Mezzanine Loan, March 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0		193,422,000
Total fixed rate | Junior Mortgage Participation, Related To Mortgage Loan, February 2019
Debt Investments Held [Abstract]
Loan acquired					5,700,000
Discount amount					$ 5,700,000
Total floating rate
Debt Investments Held [Abstract]
Future Funding Obligations	181,320,000
Senior Financing	3,498,215,000
Carrying Value	1,243,925,000		1,232,178,000
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity Date of October 2017
Debt Investments Held [Abstract]
Future Funding Obligations	622,000
Senior Financing	0
Carrying Value	23,372,000		20,423,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of December 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	85,000,000
Carrying Value	15,340,000		15,141,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of December 2017, 2
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	65,000,000
Carrying Value	14,832,000		14,656,000
Total floating rate | Mortgage Mezzanine Loan with an Initial Maturity Date of December 2017
Debt Investments Held [Abstract]
Future Funding Obligations	795,000
Senior Financing	0
Carrying Value	15,132,000		15,051,000
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity Date of January 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	125,000,000
Carrying Value	29,966,000		29,998,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of April 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	40,000,000
Carrying Value	19,964,000		19,913,000
Total floating rate | Junior Mortgage Participation Loan with an Initial Maturity Date of April 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	117,808,000
Carrying Value	34,899,000		34,844,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of August 2018
Debt Investments Held [Abstract]
Future Funding Obligations	523,000
Senior Financing	20,523,000
Carrying Value	10,916,000		10,863,000
Total floating rate | Mortgage/Mezzanine Loan, with an Initial Maturity Date of August 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	19,914,000		19,840,000
Total floating rate | Mortgage Loan with an Initial Maturity Date of August 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	65,000,000
Carrying Value	14,935,000		14,880,000
Total floating rate | Mortgage/Mezzanine Loan, September 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	16,957,000		16,960,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of September 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	37,500,000
Carrying Value	14,801,000		14,648,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of October 2018
Debt Investments Held [Abstract]
Future Funding Obligations	2,325,000
Senior Financing	45,025,000
Carrying Value	34,782,000		34,502,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of November 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	335,000,000
Carrying Value	74,683,000		74,476,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of December 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	33,000,000
Carrying Value	26,907,000		26,850,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of December 2018, 2
Debt Investments Held [Abstract]
Future Funding Obligations	1,050,000
Senior Financing	171,939,000
Carrying Value	58,598,000		56,114,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of December 2018, 3
Debt Investments Held [Abstract]
Future Funding Obligations	8,267,000
Senior Financing	289,621,000
Carrying Value	71,067,000		63,137,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of December 2018, 4
Debt Investments Held [Abstract]
Future Funding Obligations	5,197,000
Senior Financing	229,084,000
Carrying Value	74,314,000		64,505,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of January 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	45,000,000
Carrying Value	12,156,000		12,104,000
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity Date of January 2019
Debt Investments Held [Abstract]
Future Funding Obligations	30,101,000
Senior Financing	0
Carrying Value	158,757,000		0
Total floating rate | Mezzanine Loan with an Initial Maturity of January 2019, 2
Debt Investments Held [Abstract]
Future Funding Obligations	6,081,000
Senior Financing	24,086,000
Carrying Value	7,812,000		5,410,000
Total floating rate | Mezzanine Loan with an Initial Maturity of March 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	38,000,000
Carrying Value	21,927,000		21,891,000
Total floating rate | Mezzanine Loan with an Initial Maturity Date of April 2019
Debt Investments Held [Abstract]
Future Funding Obligations	279,000
Senior Financing	173,700,000
Carrying Value	36,936,000		0
Total floating rate | Mezzanine Loan with an Initial Maturity Date of April 2019, 2 [Member]
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	265,000,000
Carrying Value	24,798,000		24,707,000
Total floating rate | Mortgage/Jr Mortgage Participate Loan, Maturity Date of August 2019
Debt Investments Held [Abstract]
Future Funding Obligations	29,661,000
Senior Financing	194,094,000
Carrying Value	69,705,000		65,554,000
Total floating rate | Mezzanine Loan, Maturity of September 2019
Debt Investments Held [Abstract]
Future Funding Obligations	2,034,000
Senior Financing	187,500,000
Carrying Value	37,835,000		37,322,000
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity of September 2019
Debt Investments Held [Abstract]
Future Funding Obligations	49,933,000
Senior Financing	0
Carrying Value	130,350,000		111,819,000
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity of January 2020
Debt Investments Held [Abstract]
Future Funding Obligations	30,494,000
Senior Financing	0
Carrying Value	38,934,000		33,682,000
Total floating rate | Mezzanine Loan with an Initial Maturity of January 2020
Debt Investments Held [Abstract]
Future Funding Obligations	6,794,000
Senior Financing	537,748,000
Carrying Value	72,597,000	$ 66,100,000	125,911,000
Total floating rate | Mezzanine Loan with an Initial Maturity of July 2020 [Domain]
Debt Investments Held [Abstract]
Future Funding Obligations	7,164,000
Senior Financing	33,587,000
Carrying Value	10,988,000		0
Total floating rate | Jr Mortgage Participation/Mezzanine Loan with an Initial Maturity of July 2021
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	60,000,000
Carrying Value	15,627,000		15,606,000
Total floating 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	34,124,000		0
Total floating rate | Mezzanine Loan, with an Initial Maturity Date of September 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0		15,369,000
Total floating rate | Mortgage/Mezzanine Loan repaid in June 2017, 2
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0		32,847,000
Total floating rate | Mortgage/Mezzanine Loan repaid in June 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0		22,959,000
Total floating rate | Mezzanine Loan Contributed for a Joint Venture Interest
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0		14,957,000
Total floating rate | Mortgage/Mezzanine Loan Repaid in January 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	$ 0		$ 145,239,000

Debt and Preferred Equity Inv59

Debt and Preferred Equity Investments - Rollforward of Net Book Balance (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Mortgage Loans on Real Estate [Line Items]
Carrying Value	$ 1,640,412	$ 1,670,020
Redemptions/Sales/Syndications/Amortization	(708,180)	(1,044,482)
Carrying Value	2,020,739	1,640,412
Debt Investments in Mortgage Loans
Mortgage Loans on Real Estate [Line Items]
Originations/Accretion	944,494	1,009,176
Preferred equity investments
Mortgage Loans on Real Estate [Line Items]
Originations/Accretion	$ 144,013	$ 5,698

Debt and Preferred Equity Inv60

Debt and Preferred Equity Investments - Preferred Equity Investments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Preferred equity investment
Aggregate weighted average current yield (as a percent)	9.49%
Carrying Value	$ 2,020,739	$ 1,640,412
Preferred Equity, April 2021
Preferred equity investment
Future Funding Obligations	0
Senior Financing	272,000
Carrying Value	143,980	0
Preferred Equity redeemed in May 2017
Preferred equity investment
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	9,982
Preferred Equity redeemed in April 2017
Preferred equity investment
Future Funding Obligations	0
Senior Financing	0
Carrying Value	$ 0	37,893
Preferred equity investments
Preferred equity investment
Aggregate weighted average current yield (as a percent)	6.98%
Future Funding Obligations	$ 0
Senior Financing	272,000
Carrying Value	$ 143,980	$ 47,875

Debt and Preferred Equity Inv61

Debt and Preferred Equity Investments - Narrative (Details)	9 Months Ended	37 Months Ended
	Sep. 30, 2017USD ($)segment	Sep. 30, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Preferred equity investment
Carrying Value	$ 2,020,739,000	$ 2,020,739,000	$ 1,640,412,000
Number of portfolio segments of financial receivables (segment) | segment	1
Additional amount of financing receivables included in other assets	$ 65,600,000	65,600,000	99,500,000
Mezzanine/Jr. Mortgage Loan with an Initial Maturity Date of April 2017
Preferred equity investment
Carrying Value	250,200,000	250,200,000	0	$ 0
Junior Mortgage Participation Acquired in September 2014
Preferred equity investment
Payments to acquire loans		0
Carrying Value	0	0	$ 0	$ 0
Total fixed rate | Mezzanine/Jr. Mortgage Loan with an Initial Maturity Date of April 2017
Preferred equity investment
Receivable with Imputed Interest, Face Amount	$ 259,300,000	$ 259,300,000

Investments in Unconsolidated62

Investments in Unconsolidated Joint Ventures - Additional Information (Details) $ in Thousands	1 Months Ended
	May 31, 2017USD ($)	Oct. 31, 2016	Sep. 30, 2017USD ($)ft²unit	Apr. 30, 2017ft²	Jan. 31, 2017partner	Dec. 31, 2016USD ($)
General information on each joint venture
Net equity investment in VIEs in which the entity is not primary beneficiary | $			$ 598,700			$ 220,100
Unaudited Approximate Square Feet (sqft) | ft²			31,800,088
100 Park Avenue
General information on each joint venture
Ownership Interest			49.90%
Economic Interest (as a percent)			49.90%
Unaudited Approximate Square Feet (sqft) | ft²			834,000
Acquisition Price | $			$ 95,800
717 Fifth Avenue
General information on each joint venture
Ownership Interest			10.92%
Economic Interest (as a percent)			10.92%
Unaudited Approximate Square Feet (sqft) | ft²			119,500
Acquisition Price | $			$ 251,900
800 Third Avenue
General information on each joint venture
Ownership Interest			60.52%
Economic Interest (as a percent)			60.52%
Unaudited Approximate Square Feet (sqft) | ft²			526,000
Acquisition Price | $			$ 285,000
1745 Broadway
General information on each joint venture
Ownership Interest			56.87%
Economic Interest (as a percent)			56.87%
Unaudited Approximate Square Feet (sqft) | ft²			674,000
Acquisition Price | $			$ 520,000
Jericho Plaza
General information on each joint venture
Ownership Interest			11.67%
Economic Interest (as a percent)			11.67%
Unaudited Approximate Square Feet (sqft) | ft²			640,000
Acquisition Price | $			$ 210,000
11 West 34th Street
General information on each joint venture
Ownership Interest			30.00%
Economic Interest (as a percent)			30.00%
Unaudited Approximate Square Feet (sqft) | ft²			17,150
Acquisition Price | $			$ 10,800
3 Columbus Circle
General information on each joint venture
Ownership Interest			48.90%
Economic Interest (as a percent)			48.90%
Unaudited Approximate Square Feet (sqft) | ft²			741,500
Acquisition Price | $			$ 500,000
280 Park Avenue
General information on each joint venture
Ownership Interest			50.00%
Economic Interest (as a percent)			50.00%
Unaudited Approximate Square Feet (sqft) | ft²			1,219,158
Acquisition Price | $			$ 400,000
1552-1560 Broadway
General information on each joint venture
Ownership Interest			50.00%
Economic Interest (as a percent)			50.00%
Unaudited Approximate Square Feet (sqft) | ft²			57,718
Acquisition Price | $			$ 136,550
724 Fifth Avenue
General information on each joint venture
Ownership Interest			50.00%
Economic Interest (as a percent)			50.00%
Unaudited Approximate Square Feet (sqft) | ft²			65,010
Acquisition Price | $			$ 223,000
10 East 53rd Street
General information on each joint venture
Ownership Interest			55.00%
Economic Interest (as a percent)			55.00%
Unaudited Approximate Square Feet (sqft) | ft²			354,300
Acquisition Price | $			$ 252,500
521 Fifth Avenue
General information on each joint venture
Ownership Interest			50.50%
Economic Interest (as a percent)			50.50%
Unaudited Approximate Square Feet (sqft) | ft²			460,000
Acquisition Price | $			$ 315,000
21 East 66th Street
General information on each joint venture
Ownership Interest			32.28%
Economic Interest (as a percent)			32.28%
Unaudited Approximate Square Feet (sqft) | ft²			13,069
Acquisition Price | $			$ 75,000
650 Fifth Avenue
General information on each joint venture
Ownership Interest			50.00%
Economic Interest (as a percent)			50.00%
Unaudited Approximate Square Feet (sqft) | ft²			69,214
Acquisition Price | $			$ 0
121 Greene Street
General information on each joint venture
Ownership Interest			50.00%
Economic Interest (as a percent)			50.00%
Unaudited Approximate Square Feet (sqft) | ft²			7,131
Acquisition Price | $			$ 27,400
175-225 Third Street Brooklyn, New York
General information on each joint venture
Ownership Interest			95.00%
Economic Interest (as a percent)			95.00%
Unaudited Approximate Square Feet (sqft) | ft²			0
Acquisition Price | $			$ 74,600
55 West 46th Street
General information on each joint venture
Ownership Interest			25.00%
Economic Interest (as a percent)			25.00%
Unaudited Approximate Square Feet (sqft) | ft²			347,000
Acquisition Price | $			$ 295,000
Stonehenge Portfolio
General information on each joint venture
Ownership Interest		90.00%
Unaudited Approximate Square Feet (sqft) | ft²			1,439,016
Acquisition Price | $			$ 36,668
Stonehenge Portfolio | Joint venture
General information on each joint venture
Ownership Interest		10.00%
131-137 Spring Street
General information on each joint venture
Ownership Interest			20.00%
Economic Interest (as a percent)			20.00%
Unaudited Approximate Square Feet (sqft) | ft²			68,342
Acquisition Price | $			$ 277,750
605 West 42nd Street
General information on each joint venture
Ownership Interest			20.00%
Economic Interest (as a percent)			20.00%
Unaudited Approximate Square Feet (sqft) | ft²			927,358
Acquisition Price | $			$ 759,000
11 Madison Avenue
General information on each joint venture
Ownership Interest			60.00%
Economic Interest (as a percent)			60.00%
Unaudited Approximate Square Feet (sqft) | ft²			2,314,000
Acquisition Price | $			$ 2,605,000
333 East 22nd St
General information on each joint venture
Ownership Interest			33.33%
Economic Interest (as a percent)			33.33%
Unaudited Approximate Square Feet (sqft) | ft²			26,926
Acquisition Price | $			$ 0
East 400 Street 57
General information on each joint venture
Ownership Interest		51.00%	51.00%
Economic Interest (as a percent)			41.00%
Unaudited Approximate Square Feet (sqft) | ft²			290,482
Acquisition Price | $			$ 170,000
1552 Broadway
General information on each joint venture
Unaudited Approximate Square Feet (sqft) | ft²			13,045
One Vanderbilt
General information on each joint venture
Ownership Interest			71.01%
Economic Interest (as a percent)			71.01%
Unaudited Approximate Square Feet (sqft) | ft²			0
Acquisition Price | $			$ 3,310,000
Number of joint venture partners | partner					2
Aggregate equity committed by partners | $			$ 525,000
Maximum ownership percentage of partners			29.00%
Partners' ownership percentage			3.49%
Equity method investment, amount sold | $	$ 10,000
102 Greene Street
General information on each joint venture
Ownership Interest			10.00%
East 400 Street 57
General information on each joint venture
Ownership percentage in disposed asset		49.00%
102 Greene Street
General information on each joint venture
Unaudited Approximate Square Feet (sqft) | ft²				9,200
21 East 66th Street | Three Retail and Two Residential Units
General information on each joint venture
Ownership Interest			3228.00%
Number of stores | unit			3
Number of residential units | unit			2
21 East 66th Street | Three Residential Units
General information on each joint venture
Ownership Interest			1614.00%
Number of residential units | unit			3
Mezzanine Loan
General information on each joint venture
Ownership Interest	33.33%		33.33%
Economic Interest (as a percent)			33.33%
Unaudited Approximate Square Feet (sqft) | ft²			0
Acquisition Price | $			$ 15,000

Investments in Unconsolidated63

Investments in Unconsolidated Joint Ventures - Acquisition, Development and Construction Arrangements/Sale of Joint Venture Interest or Property (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	May 31, 2017note	Dec. 31, 2016USD ($)	Oct. 31, 2016
Schedule of Equity Method Investments [Line Items]
Acquisition, development and construction arrangements, carrying value	$ 170,735		$ 170,735			$ 170,164
Gain (loss) on sale of real estate, net	0	$ 397	(3,256)	$ 210,750
Mezzanine Loan and Preferred Equity Due March 2018
Schedule of Equity Method Investments [Line Items]
Acquisition, development and construction arrangements, carrying value	100,000		100,000			100,000
Mezzanine loan due February 2022
Schedule of Equity Method Investments [Line Items]
Acquisition, development and construction arrangements, carrying value	44,881		44,881			45,622
Mezzanine loan due July 2036
Schedule of Equity Method Investments [Line Items]
Acquisition, development and construction arrangements, carrying value	25,854		25,854			$ 24,542
Stonehenge Portfolio
Schedule of Equity Method Investments [Line Items]
Ownership Interest							90.00%
Gross Asset Valuation	$ 300,000		300,000
Gain on Sale			$ 871
102 Greene Street
Schedule of Equity Method Investments [Line Items]
Ownership Interest	10.00%		10.00%
Gross Asset Valuation	$ 43,500		$ 43,500
Gain on Sale			$ 283
747 Madison Avenue
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale of real estate, net	$ 13,000
76 11th Avenue
Schedule of Equity Method Investments [Line Items]
Number of notes owned by joint venture partner | note					2

Investments in Unconsolidated64

Investments in Unconsolidated Joint Ventures - Mortgages and Other Loans Payable (Details)	9 Months Ended
	Sep. 30, 2017USD ($)extenstion_option	Oct. 31, 2017USD ($)	Aug. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Debt Instrument [Line Items]
Total fixed rate debt	$ 3,286,248,000			$ 3,518,127,000
Total floating rate debt	558,813,000			622,585,000
Total fixed rate and floating rate debt	$ 3,845,061,000			4,140,712,000
Number of extension options | extenstion_option	2
Period of extension options	1 year
521 Fifth Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.50%
717 Fifth Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	10.92%
650 Fifth Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.00%
21 East 66th Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	32.28%
3 Columbus Circle
Debt Instrument [Line Items]
Economic Interest (as a percent)	48.90%
11 Madison Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	60.00%
800 Third Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	60.52%
East 400 Street 57
Debt Instrument [Line Items]
Economic Interest (as a percent)	41.00%
1745 Broadway
Debt Instrument [Line Items]
Economic Interest (as a percent)	56.87%
55 West 46th Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	25.00%
175-225 Third Street Brooklyn, New York
Debt Instrument [Line Items]
Economic Interest (as a percent)	95.00%
Jericho Plaza
Debt Instrument [Line Items]
Economic Interest (as a percent)	11.67%
724 Fifth Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.00%
1552 Broadway
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.00%
280 Park Avenue (9)
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.00%
121 Greene Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	50.00%
10 East 53rd Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	55.00%
131-137 Spring Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	20.00%
11 West 34th Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	30.00%
100 Park Avenue
Debt Instrument [Line Items]
Economic Interest (as a percent)	49.90%
One Vanderbilt
Debt Instrument [Line Items]
Economic Interest (as a percent)	71.01%
Total floating rate debt	$ 0			64,030,000
One Vanderbilt | Construction Loans
Debt Instrument [Line Items]
Term (in Years)	5 years
Maximum facility capacity	$ 1,500,000,000
Credit facility, interest rate (as a percent)	3.50%
Number of extension options | extenstion_option	2
Period of extension options	1 year
605 West 42nd Street
Debt Instrument [Line Items]
Economic Interest (as a percent)	20.00%
Joint venture
Debt Instrument [Line Items]
Total fixed rate debt	$ 3,448,423,000			3,566,846,000
Total floating rate debt	3,877,504,000			2,982,528,000
Total fixed rate and floating rate debt	7,325,927,000			6,549,374,000
Deferred financing costs, net	(127,318,000)			(95,408,000)
Total joint venture mortgages and other loans payable, net	7,198,609,000			6,453,966,000
Joint venture | 521 Fifth Avenue
Debt Instrument [Line Items]
Total fixed rate debt	170,000,000			170,000,000
Joint venture | 717 Fifth Avenue | Mortgage loan
Debt Instrument [Line Items]
Committed amount	300,000,000
Joint venture | 717 Fifth Avenue | Mezzanine loans
Debt Instrument [Line Items]
Committed amount	355,300,000
Joint venture | 717 Fifth Avenue | Initial Maturity July 2022
Debt Instrument [Line Items]
Total fixed rate debt	300,000,000			300,000,000
Joint venture | 717 Fifth Avenue | Initial Maturity July 2022, 2
Debt Instrument [Line Items]
Total fixed rate debt	355,328,000			355,328,000
Joint venture | 650 Fifth Avenue
Debt Instrument [Line Items]
Total floating rate debt	0			77,500,000
Joint venture | 650 Fifth Avenue | Initial Maturity October 2022
Debt Instrument [Line Items]
Total fixed rate debt	225,000,000			0
Joint venture | 21 East 66th Street
Debt Instrument [Line Items]
Total fixed rate debt	12,000,000			12,000,000
Total floating rate debt	1,667,000			1,726,000
Joint venture | 3 Columbus Circle
Debt Instrument [Line Items]
Total fixed rate debt	350,000,000			350,000,000
Joint venture | 11 Madison Avenue
Debt Instrument [Line Items]
Total fixed rate debt	1,400,000,000			1,400,000,000
Joint venture | 800 Third Avenue
Debt Instrument [Line Items]
Total fixed rate debt	177,000,000			177,000,000
Joint venture | East 400 Street 57
Debt Instrument [Line Items]
Total fixed rate debt	100,000,000			100,000,000
Joint venture | Stonehenge Portfolio
Debt Instrument [Line Items]
Total fixed rate debt	359,095,000			362,518,000
Total floating rate debt	55,340,000			65,577,000
Joint venture | Stonehenge Portfolio | Initial Maturity November 2017
Debt Instrument [Line Items]
Total fixed rate debt	34,000,000
Joint venture | Stonehenge Portfolio | Initial Maturity August 2019
Debt Instrument [Line Items]
Total fixed rate debt	137,700,000
Joint venture | Stonehenge Portfolio | Initial Maturity June 2024
Debt Instrument [Line Items]
Total fixed rate debt	172,500,000
Joint venture | Stonehenge Portfolio | Initial Maturity February 2027
Debt Instrument [Line Items]
Total fixed rate debt	14,900,000
Joint venture | 1745 Broadway
Debt Instrument [Line Items]
Total fixed rate debt	0			340,000,000
Total floating rate debt	345,000,000			0
Joint venture | 1745 Broadway | Mortgage loan
Debt Instrument [Line Items]
Committed amount	375,000,000
Unfunded amount	30,000,000
Joint venture | 55 West 46th Street
Debt Instrument [Line Items]
Total floating rate debt	165,328,000			157,322,000
Joint venture | 55 West 46th Street | Mortgage loan
Debt Instrument [Line Items]
Committed amount	190,000,000
Unfunded amount	24,700,000
Joint venture | 175-225 Third Street Brooklyn, New York
Debt Instrument [Line Items]
Total floating rate debt	40,000,000			40,000,000
Joint venture | Jericho Plaza
Debt Instrument [Line Items]
Total floating rate debt	$ 79,530,000			76,993,000
Term (in Years)	2 years
Face amount of loan	$ 100,000,000
Joint venture | 724 Fifth Avenue
Debt Instrument [Line Items]
Total floating rate debt	275,000,000			275,000,000
Joint venture | 1552 Broadway
Debt Instrument [Line Items]
Total floating rate debt	185,410,000			185,410,000
Joint venture | 1552 Broadway | Mortgage loan
Debt Instrument [Line Items]
Committed amount	145,000,000
Unfunded amount	600,000
Joint venture | 1552 Broadway | Mezzanine loans
Debt Instrument [Line Items]
Committed amount	41,500,000
Unfunded amount	500,000
Joint venture | 280 Park Avenue (9)
Debt Instrument [Line Items]
Total floating rate debt	1,200,000,000			900,000,000
Joint venture | 280 Park Avenue (9) | Mortgage loan
Debt Instrument [Line Items]
Committed amount			$ 1,075,000,000
Joint venture | 280 Park Avenue (9) | Mezzanine loans
Debt Instrument [Line Items]
Committed amount			125,000,000
Joint venture | 121 Greene Street
Debt Instrument [Line Items]
Total floating rate debt	15,000,000			15,000,000
Joint venture | 10 East 53rd Street
Debt Instrument [Line Items]
Total floating rate debt	170,000,000			125,000,000
Joint venture | 131-137 Spring Street
Debt Instrument [Line Items]
Total floating rate debt	141,000,000			141,000,000
Joint venture | 11 West 34th Street
Debt Instrument [Line Items]
Total floating rate debt	23,000,000			23,000,000
Joint venture | 100 Park Avenue
Debt Instrument [Line Items]
Total floating rate debt	360,000,000			360,000,000
Joint venture | One Vanderbilt
Debt Instrument [Line Items]
Total floating rate debt	271,229,000			0
Joint venture | 605 West 42nd Street
Debt Instrument [Line Items]
Total floating rate debt	$ 550,000,000			$ 539,000,000
Joint venture | 605 West 42nd Street | Mortgage loan
Debt Instrument [Line Items]
Committed amount			$ 550,000,000
Weighted Average | One Vanderbilt
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)
Weighted Average | Joint venture | 521 Fifth Avenue
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.73%
Weighted Average | Joint venture | 717 Fifth Avenue | Initial Maturity July 2022
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.45%
Weighted Average | Joint venture | 717 Fifth Avenue | Initial Maturity July 2022, 2
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	5.50%
Weighted Average | Joint venture | 650 Fifth Avenue | Initial Maturity October 2022
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.95%
Weighted Average | Joint venture | 21 East 66th Street
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.60%
Interest rate, floating rate debt (as a percent)	3.62%
Weighted Average | Joint venture | 3 Columbus Circle
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.61%
Weighted Average | Joint venture | 11 Madison Avenue
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.84%
Weighted Average | Joint venture | 800 Third Avenue
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.37%
Weighted Average | Joint venture | East 400 Street 57
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.00%
Weighted Average | Joint venture | Stonehenge Portfolio
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.17%
Interest rate, floating rate debt (as a percent)	2.47%
Weighted Average | Joint venture | 1745 Broadway
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	3.07%
Weighted Average | Joint venture | 55 West 46th Street
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	3.52%
Weighted Average | Joint venture | 175-225 Third Street Brooklyn, New York
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	5.25%
Weighted Average | Joint venture | Jericho Plaza
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	5.37%
Weighted Average | Joint venture | 724 Fifth Avenue
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	3.64%
Weighted Average | Joint venture | 1552 Broadway
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	5.41%
Weighted Average | Joint venture | 280 Park Avenue (9)
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	3.09%
Weighted Average | Joint venture | 121 Greene Street
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	2.72%
Weighted Average | Joint venture | 10 East 53rd Street
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	3.47%
Weighted Average | Joint venture | 131-137 Spring Street
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	2.77%
Weighted Average | Joint venture | 11 West 34th Street
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	2.68%
Weighted Average | Joint venture | 100 Park Avenue
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	2.97%
Weighted Average | Joint venture | One Vanderbilt
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	4.72%
Weighted Average | Joint venture | 605 West 42nd Street
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	2.84%
LIBOR | Joint venture | 280 Park Avenue (9) | Mortgage loan
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)			1.48%
LIBOR | Joint venture | 280 Park Avenue (9) | Mezzanine loans
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)			3.85%
LIBOR | Joint venture | 605 West 42nd Street | Mortgage loan
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)			1.44%
Subsequent Event | Joint venture | 55 West 46th Street | Mortgage loan
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)		2.13%
Committed amount		$ 195,000,000
Subsequent Event | Joint venture | 1552 Broadway | Mortgage loan
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)		2.65%
Committed amount		$ 195,000,000

Investments in Unconsolidated65

Investments in Unconsolidated Joint Ventures - Schedules of Combined Financial Statements for the Unconsolidated Joint Ventures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Assets
Commercial real estate property, net	$ 9,421,501		$ 9,421,501		$ 10,478,638
Cash and cash equivalents	241,489	$ 405,896	241,489	$ 405,896	279,443	$ 255,399
Tenant and other receivables, related party receivables, and deferred rents receivable, net of allowance	54,663		54,663		53,772
Other assets	395,612		395,612		614,067
Liabilities and members' equity
Mortgages and other loans payable, net	3,804,174		3,804,174		4,073,830
Deferred revenue/gain	252,779		252,779		217,955
Other liabilities	95,718		95,718		206,238
Company's investments in unconsolidated joint ventures	2,045,796		2,045,796		1,890,186
Combined statements of income for the unconsolidated joint ventures
Operating expenses	75,927	79,425	221,285	234,269
Ground rent	8,307	8,338	24,923	24,953
Real estate taxes	64,160	64,133	186,173	187,931
Interest expense, net of interest income	65,634	72,565	196,112	256,326
Amortization of deferred financing costs	4,008	4,815	12,201	20,180
Transaction related costs	186	2,593	365	5,987
Depreciation and amortization	91,728	112,665	318,916	717,015
Total expenses	333,913	369,992	1,032,337	1,520,635
Company's equity in net income (loss) from unconsolidated joint ventures	4,078	(3,968)	14,104	11,969
Joint venture
Investment in Unconsolidated Joint Ventures
Management fees, base revenue	2,900	2,000	28,100	4,500
Assets
Commercial real estate property, net	9,944,280		9,944,280		9,131,717
Cash and cash equivalents	370,596		370,596		328,455
Tenant and other receivables, related party receivables, and deferred rents receivable, net of allowance	267,244		267,244		232,778
Debt and preferred equity investments, net	201,731		201,731		336,164
Other assets	636,365		636,365		683,481
Total assets	11,420,216		11,420,216		10,712,595
Liabilities and members' equity
Mortgages and other loans payable, net	7,198,609		7,198,609		6,453,966
Deferred revenue/gain	340,310		340,310		356,414
Other liabilities	411,261		411,261		391,500
Members' equity	3,470,036		3,470,036		3,510,715
Total liabilities and members' equity	11,420,216		11,420,216		$ 10,712,595
Combined statements of income for the unconsolidated joint ventures
Total revenues	216,100	184,221	643,210	498,308
Operating expenses	38,055	34,727	115,996	89,147
Ground rent	4,182	3,744	12,612	10,670
Real estate taxes	37,282	30,814	107,391	79,356
Interest expense, net of interest income	61,066	51,789	176,096	147,876
Amortization of deferred financing costs	4,030	7,155	17,994	17,667
Transaction related costs	0	5,359	146	5,359
Depreciation and amortization	61,447	56,890	198,556	132,035
Total expenses	206,062	190,478	628,791	482,110
Loss on early extinguishment of debt	(7,638)	0	(7,638)	(1,606)
Net income (loss) before gain on sale	2,400	(6,257)	6,781	14,592
Company's equity in net income (loss) from unconsolidated joint ventures	$ 4,078	$ (3,968)	$ 14,104	$ 11,969

Deferred Costs (Details)

Deferred Costs (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred leasing costs	$ 464,788	$ 468,971
Less: accumulated amortization	(216,807)	(201,371)
Deferred costs, net	$ 247,981	$ 267,600

Mortgages and Other Loans Pay67

Mortgages and Other Loans Payable (Details)	9 Months Ended
	Sep. 30, 2017USD ($)extenstion_optiondebt_instrument$ / shares	Jan. 31, 2017partner	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)
Debt Instrument [Line Items]
Total fixed rate debt	$ 3,286,248,000		$ 3,518,127,000
Total floating rate debt	558,813,000		622,585,000
Total fixed rate and floating rate debt	3,845,061,000		4,140,712,000
Mortgages reclassed to liabilities related to assets held for sale	0		0
Total mortgages and other loans payable	3,845,061,000		4,140,712,000
Deferred financing costs, net of amortization	(40,887,000)		(66,882,000)
Total mortgages and other loans payable, net	3,804,174,000		4,073,830,000
Book value of collateral	$ 6,700,000,000		6,000,000,000
Number of extension options | extenstion_option	2
Period of extension options	1 year
Outstanding under line of credit facility	$ 275,832,000		0
Series J Preferred Units
Debt Instrument [Line Items]
Total fixed rate debt	4,000,000		4,000,000
Limited partnership interest	$ 4,000,000
Preferred units (as a percent)	3.75%
Preferred units, liquidation preference (in dollars per unit) | $ / shares	$ 1,000
Series J Preferred Units | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.75%
Unsecured Loan
Debt Instrument [Line Items]
Total fixed rate debt	$ 16,000,000		16,000,000
Unsecured Loan | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.81%
FHLB Advance Maturing in January 2017
Debt Instrument [Line Items]
Total fixed rate debt	$ 0		105,000,000
FHLB Advance Maturing in January 2017, 2
Debt Instrument [Line Items]
Total fixed rate debt	0		100,000,000
Master Repurchase Agreement
Debt Instrument [Line Items]
Total floating rate debt	$ 184,642,000		184,642,000
Term (in Years)	2 years
Maximum facility capacity	$ 300,000,000
Period of extension options	1 year
Basis point fee (as a percent)	0.25%
Outstanding under line of credit facility	$ 182,800,000
Threshold amount for basis point fee to be applicable (less than)	$ 150,000,000
Master Repurchase Agreement | Weighted Average
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	3.73%
Master Repurchase Agreement | Minimum | LIBOR
Debt Instrument [Line Items]
Credit facility, interest rate (as a percent)	2.25%
Master Repurchase Agreement | Maximum | LIBOR
Debt Instrument [Line Items]
Credit facility, interest rate (as a percent)	4.00%
Uncommitted Master Repurchase Agreements
Debt Instrument [Line Items]
Number of debt instruments | debt_instrument	2
Uncommitted Master Repurchase Agreement, 2
Debt Instrument [Line Items]
Term (in Years)	1 year
Maximum facility capacity	$ 300,000,000
Outstanding under line of credit facility	(1,100,000)
One Madison Avenue
Debt Instrument [Line Items]
Total fixed rate debt	$ 494,264,000		517,806,000
One Madison Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	5.91%
762 Madison Avenue
Debt Instrument [Line Items]
Total fixed rate debt	$ 771,000		7,694,000
762 Madison Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	5.00%
100 Church Street
Debt Instrument [Line Items]
Total fixed rate debt	$ 218,237,000		221,446,000
100 Church Street | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.68%
919 Third Avenue
Debt Instrument [Line Items]
Total fixed rate debt	$ 500,000,000		500,000,000
Interest in property (as a percent)	51.00%
919 Third Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	5.12%
420 Lexington Avenue
Debt Instrument [Line Items]
Total fixed rate debt	$ 300,000,000		300,000,000
420 Lexington Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.99%
1515 Broadway
Debt Instrument [Line Items]
Total fixed rate debt	$ 876,613,000		888,531,000
1515 Broadway | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.93%
400 East 58th Street
Debt Instrument [Line Items]
Total fixed rate debt	$ 40,000,000		40,000,000
400 East 58th Street | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.00%
Term (in Years)	5 years
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	$ 36,363,000		0
Total fixed rate debt	35,500,000
Subordinate loan	$ 900,000
1080 Amsterdam Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	3.58%
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%
315 West 33rd Street
Debt Instrument [Line Items]
Total fixed rate debt	$ 250,000,000		0
315 West 33rd Street | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)	4.17%
885 Third Avenue
Debt Instrument [Line Items]
Total fixed rate debt	$ 0		267,650,000
885 Third Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, fixed rate debt (as a percent)
719 Seventh Avenue
Debt Instrument [Line Items]
Total floating rate debt	$ 41,171,000		37,388,000
719 Seventh Avenue | Weighted Average
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	4.27%
183, 187 Broadway & 5-7 Dey Street
Debt Instrument [Line Items]
Total floating rate debt	$ 58,000,000		58,000,000
183, 187 Broadway & 5-7 Dey Street | Weighted Average
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	3.92%
220 East 42nd Street
Debt Instrument [Line Items]
Total floating rate debt	$ 275,000,000		275,000,000
220 East 42nd Street | Weighted Average
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)	2.82%
One Vanderbilt
Debt Instrument [Line Items]
Total floating rate debt	$ 0		64,030,000
Number of joint venture partners | partner		2
One Vanderbilt | Weighted Average
Debt Instrument [Line Items]
Interest rate, floating rate debt (as a percent)
One Vanderbilt | Construction Loans
Debt Instrument [Line Items]
Maximum facility capacity				$ 1,500,000,000
Number of joint venture partners | partner		2
1080 Amsterdam
Debt Instrument [Line Items]
Total floating rate debt	$ 0		$ 3,525,000

Corporate Indebtedness - Additi

Corporate Indebtedness - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Corporate Indebtedness
Outstanding under line of credit facility	$ 275,832,000	$ 0
Long-term debt, carrying value	6,477,061,000
Revolving credit facility
Corporate Indebtedness
Credit facility, maximum borrowing capacity	1,600,000,000
Maximum borrowing capacity, optional expansion	$ 3,000,000,000
Effective rate (as a percent)	2.49%
Facility fee (as a percent)	0.25%
Outstanding under line of credit facility	$ 280,000,000
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%
Revolving credit facility | LIBOR
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.25%
Revolving credit facility | LIBOR | Minimum
Corporate Indebtedness
Interest rate added to base rate (as a percent)	0.875%
Revolving credit facility | LIBOR | Maximum
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.55%
Term loan
Corporate Indebtedness
Credit facility, maximum borrowing capacity	$ 1,200,000,000
Effective rate (as a percent)	2.49%
Long-term debt, carrying value	$ 1,183,000,000
Term loan | Line of Credit
Corporate Indebtedness
Long-term debt, carrying value	$ 1,200,000,000	1,200,000,000
Term loan | LIBOR
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.40%
Term loan | LIBOR | Minimum
Corporate Indebtedness
Interest rate added to base rate (as a percent)	0.95%
Term loan | LIBOR | Maximum
Corporate Indebtedness
Interest rate added to base rate (as a percent)	1.90%
2012 Credit Facility
Corporate Indebtedness
Letters of credit	$ 80,800,000
Ability to borrow under line of credit facility	1,200,000,000
Long-term debt, carrying value	280,000,000
2012 Credit Facility | Line of Credit
Corporate Indebtedness
Long-term debt, carrying value	$ 275,800,000	$ (6,300,000)

Corporate Indebtedness - Senior

Corporate Indebtedness - Senior Unsecured Notes (Details) - USD ($)	1 Months Ended	9 Months Ended
	Oct. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Debt disclosures by scheduled maturity date
Accreted Balance		$ 1,180,506,000	$ 1,179,521,000
Senior unsecured notes
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		1,069,000,000
Accreted Balance		1,068,562,000	1,133,957,000
Deferred financing costs, net		(4,018,000)	(5,642,000)
Accreted Balance, net of deferred financing costs		1,064,544,000	1,128,315,000
Senior unsecured notes | 3.00% Senior unsecured notes maturing on October 15, 2017
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		269,000,000
Accreted Balance		$ 268,628,000	334,077,000
Coupon Rate (as a percent)		3.00%
Effective rate (as a percent)		3.00%
Initial Term (in Years)		7 years
Senior unsecured notes | 5.00% Senior unsecured notes maturing on August 15, 2018
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		$ 250,000,000
Accreted Balance		$ 249,934,000	249,880,000
Coupon Rate (as a percent)		5.00%
Effective rate (as a percent)		5.00%
Initial Term (in Years)		7 years
Senior unsecured notes | 7.75% Senior unsecured notes maturing on March 15, 2020
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		$ 250,000,000
Accreted Balance		$ 250,000,000	250,000,000
Coupon Rate (as a percent)		7.75%
Effective rate (as a percent)		7.75%
Initial Term (in Years)		10 years
Senior unsecured notes | 4.50% Senior unsecured notes maturing on December 1, 2022
Debt disclosures by scheduled maturity date
Unpaid Principal Balance		$ 200,000,000
Accreted Balance		$ 200,000,000	200,000,000
Coupon Rate (as a percent)		4.50%
Effective rate (as a percent)		4.50%
Initial Term (in Years)		10 years
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%
Effective rate (as a percent)		4.27%
Initial Term (in Years)		10 years
Subsequent Event | Senior unsecured notes | 3.00% Senior unsecured notes maturing on October 15, 2017
Debt disclosures by scheduled maturity date
Repayments of debt	$ 350,800,000
Subsequent Event | Senior unsecured notes | 3.25 Percent Senior Unsecured Notes Due October 2022
Debt disclosures by scheduled maturity date
Coupon Rate (as a percent)	3.25%
Face amount of loan	$ 500,000,000
Subsequent Event | Senior Unsecured Bonds | 4.50% Senior Unsecured Bonds Due December 2022
Debt disclosures by scheduled maturity date
Coupon Rate (as a percent)	4.50%
Effective rate (as a percent)	3.298%
Face amount of loan	$ 100,000,000
Redemption price, percentage	105.334%

Corporate Indebtedness - Junior

Corporate Indebtedness - Junior Subordinated Deferrable Interest Debentures and Principal Maturities (Details) - USD ($)	1 Months Ended	9 Months Ended
	Jun. 30, 2005	Sep. 30, 2017
Scheduled Amortization and Principal Repayments
Remaining 2,017		$ 281,846,000
2,018		604,750,000
2,019		1,242,618,000
2,020		1,250,958,000
2,021		30,418,000
Thereafter		3,066,471,000
Total amortization of debt and principal repayments		6,477,061,000
Joint Venture Debt
Principal Repayments and Joint Venture Debt
Remaining 2,017		79,787,000
2,018		242,799,000
2,019		705,574,000
2,020		320,914,000
2,021		376,765,000
Thereafter		1,465,371,000
Total principal repayments		3,191,210,000
Trust Preferred Securities
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 100,000,000
Scheduled Amortization and Principal Repayments
Remaining 2,017		0
2,018		0
2,019		0
2,020		0
2,021		0
Thereafter		100,000,000
Total amortization of debt and principal repayments		100,000,000
Mortgages and other loans payable
Scheduled Amortization
Remaining 2,017		12,846,000
2,018		54,937,000
2,019		59,618,000
2,020		41,427,000
2,021		30,418,000
Thereafter		90,532,000
Total amortization of debt		289,778,000
Principal Repayments and Joint Venture Debt
Remaining 2,017		0
2,018		299,813,000
2,019		0
2,020		679,531,000
2,021		0
Thereafter		2,575,939,000
Total principal repayments		3,555,283,000
Revolving Credit Facility
Scheduled Amortization and Principal Repayments
Remaining 2,017		0
2,018		0
2,019		0
2,020		280,000,000
2,021		0
Thereafter		0
Total amortization of debt and principal repayments		280,000,000
Unsecured Term Loan
Scheduled Amortization and Principal Repayments
Remaining 2,017		0
2,018		0
2,019		1,183,000,000
2,020		0
2,021		0
Thereafter		0
Total amortization of debt and principal repayments		1,183,000,000
Senior Unsecured Notes
Scheduled Amortization and Principal Repayments
Remaining 2,017		269,000,000
2,018		250,000,000
2,019		0
2,020		250,000,000
2,021		0
Thereafter		300,000,000
Total amortization of debt and principal repayments		$ 1,069,000,000
LIBOR | Trust Preferred Securities
Debt Instrument [Line Items]
Interest rate added to base rate (as a percent)		1.25%
Effective interest rate (as a percent)		2.52%
LIBOR | Unsecured Term Loan
Debt Instrument [Line Items]
Interest rate added to base rate (as a percent)		1.40%

Corporate Indebtedness - Schedu

Corporate Indebtedness - Schedule of Consolidated Interest Expense, Excluding Capitalized Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Interest expense
Interest expense before capitalized interest	$ 72,859	$ 78,715	$ 217,273	$ 276,437
Interest capitalized	(6,869)	(6,084)	(19,892)	(18,135)
Interest income	(356)	(66)	(1,269)	(1,976)
Interest expense, net	$ 65,634	$ 72,565	$ 196,112	$ 256,326

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017
Amounts due from/to related parties
Due from joint ventures	$ 1,240	$ 16,736		$ 16,736
Other	14,616	7,332		7,332
Related party receivables	$ 15,856	24,068		24,068
Alliance Building Services
Related Party Transactions
Profit participation from related party		1,000	$ 800	3,000	$ 2,600
Payments made for services		5,700	5,300	16,000	16,100
Entity with Stephen L Green ownership interest
Related Party Transactions
Property management fees from related party		100	$ 100	400	$ 300
One Vanderbilt
Related Party Transactions
Due from related party, percentage received (as a percentage)	50.00%
One Vanderbilt | Marc Holliday
Related Party Transactions
Due from related party		1,400		1,400
One Vanderbilt | Andrew Mathias
Related Party Transactions
Due from related party		$ 1,000		$ 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%
Scenario, Forecast | One Vanderbilt
Related Party Transactions
Due from related party, percentage received (as a percentage)						50.00%

Noncontrolling Interests on t73

Noncontrolling Interests on the Company's Consolidated Financial Statements - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)shares$ / shares	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)shares$ / shares	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)shares	Mar. 31, 2016shares	Aug. 31, 2015shares	Jul. 31, 2015shares	Jun. 30, 2015shares	Feb. 28, 2015shares	Aug. 31, 2014shares
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Balance at beginning of period | $			$ 473,882,000
Net income | $	$ 1,812,000	$ 1,663,000	2,707,000	$ 8,171,000
Accumulated other comprehensive income allocation | $	(4,000)	118,000	(303,000)	(257,000)
Balance at end of period | $	$ 470,898,000		$ 470,898,000		$ 473,882,000
Number of company common stock issued on conversion of Series B preferred units			6.71348
SL Green Operating Partnership
Organization
Noncontrolling interest in the operating partnership (as a percent)	4.45%		4.45%		4.16%
Number of units of operating partnership owned by the noncontrolling interest unit holders (shares) | shares	4,541,765		4,541,765		4,363,716
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares) | shares	4,541,765		4,541,765
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Balance at beginning of period | $			$ 473,882,000	424,206,000	$ 424,206,000
Distributions | $			(10,639,000)		(12,671,000)
Issuance of common units | $			23,273,000		78,495,000
Redemption of common units | $			(15,353,000)		(31,805,000)
Net income | $			2,707,000		10,136,000
Accumulated other comprehensive income allocation | $	$ (4,000)	$ 118,000	(303,000)	$ (257,000)	1,299,000
Fair value adjustment | $			(2,669,000)		4,222,000
Balance at end of period | $	$ 470,898,000		$ 470,898,000		$ 473,882,000
SL Green Operating Partnership | Series G Preferred Units
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares	1,902,000		1,902,000
Dividend rate preferred units (as a percent)			4.50%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			1.125
Operating partnership common stock value use for conversion of preferred units (in dollars per share)	$ 88.50		$ 88.50
Number of company common stock issue on redemption of operation partnership common units			1
SL Green Operating Partnership | Series F Preferred Units
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares	60		60
Mandatory liquidation preference (in dollars per share) | $	$ 1,000		$ 1,000
SL Green Operating Partnership | Series K Preferred Units
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares											563,954
Dividend rate preferred units (as a percent)			3.50%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			0.875
Operating partnership common stock value use for conversion of preferred units (in dollars per share)	$ 134.67		$ 134.67
Preferred units, shares authorized (in shares) | shares	700,000		700,000
SL Green Operating Partnership | Series L Preferred Units
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares											378,634
Dividend rate preferred units (as a percent)			4.00%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			$ 1
Preferred units, shares authorized (in shares) | shares	500,000		500,000
SL Green Operating Partnership | Series M Preferred Units
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares										1,600,000
Dividend rate preferred units (as a percent)			3.75%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			$ 0.9375
Preferred units, shares authorized (in shares) | shares	1,600,000		1,600,000
SL Green Operating Partnership | Series N Preferred Units
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares									552,303
Dividend rate preferred units (as a percent)			3.00%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			$ 0.75
Preferred units, shares authorized (in shares) | shares	552,303		552,303
SL Green Operating Partnership | Series O Preferred Units
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Dividend rate preferred units (as a percent)			6.25%
Preferred units, shares authorized (in shares) | shares	1		1
SL Green Operating Partnership | Series P Preferred Units
Organization
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares) | shares	200,000		200,000
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares								200,000
Dividend rate preferred units (as a percent)			4.00%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			$ 1
SL Green Operating Partnership | Series Q Preferred Units
Organization
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares) | shares	268,000		268,000
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares								268,000
Dividend rate preferred units (as a percent)			3.50%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			0.875
Operating partnership common stock value use for conversion of preferred units (in dollars per share)	$ 148.95		$ 148.95
SL Green Operating Partnership | Series R Preferred Units
Organization
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares) | shares	400,000		400,000
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares							400,000
Dividend rate preferred units (as a percent)			3.50%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			0.875
Operating partnership common stock value use for conversion of preferred units (in dollars per share)	$ 154.89		$ 154.89
SL Green Operating Partnership | Series S Preferred Units
Organization
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares) | shares	1,077,280		1,077,280
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares							1,077,280
Dividend rate preferred units (as a percent)			4.00%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			$ 1
SL Green Operating Partnership | Series T Preferred Units
Organization
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares) | shares	230,000		230,000
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares						230,000
Dividend rate preferred units (as a percent)			2.75%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			0.6875
Operating partnership common stock value use for conversion of preferred units (in dollars per share)	$ 119.02		$ 119.02
SL Green Operating Partnership | Series U Preferred Units
Organization
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares) | shares	680,000		680,000
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares						680,000
Dividend rate preferred units (as a percent)			4.50%
Liquidation preference of preferred units (in dollars per share)	$ 25		$ 25
Annual dividends on preferred units (in dollars per share)			1.125
SL Green Operating Partnership | Series U Preferred Units | Minimum
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Annual dividends on preferred units (in dollars per share)			$ 0.75
SL Green Operating Partnership | Series A Preferred Units
Organization
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares) | shares	109,161		109,161
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares							109,161
Dividend rate preferred units (as a percent)			3.50%
Liquidation preference of preferred units (in dollars per share)	$ 1,000		$ 1,000
Annual dividends on preferred units (in dollars per share)			$ 35
SL Green Operating Partnership | Series B Preferred Units
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of preferred units issued (in shares) | shares	0		0

Noncontrolling Interests on t74

Noncontrolling Interests on the Company's Consolidated Financial Statements - Common Unit Activity (Details) - SL Green Operating Partnership - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Rollforward Analysis of Preferred Unit Activity
Issuance of preferred units	$ 23,273	$ 78,495
Redemption of preferred units	(15,353)	(31,805)
Preferred Units
Rollforward Analysis of Preferred Unit Activity
Balance at beginning of period	302,010	282,516
Issuance of preferred units	0	22,793
Redemption of preferred units	(125)	(3,299)
Balance at end of period	$ 301,885	$ 302,010

Stockholders' Equity of the C75

Stockholders' Equity of the Company - Additional Information (Details) - USD ($)	3 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Aug. 31, 2016
Equity, Class of Treasury Stock [Line Items]
Authorized capital stock (shares)	260,000,000
Authorized shares, par value (in dollars per share)	$ 0.01
Common stock, shares authorized (in shares)	160,000,000			160,000,000
Common stock, par value (in dollars per share)	$ 0.01			$ 0.01
Excess stock, shares authorized (shares)	75,000,000
Excess stock, par value (in dollars per share)	$ 0.01
Preferred stock, shares authorized (shares)	25,000,000
Preferred stock, par value (in dollars per share)	$ 0.01
Excess shares issued (shares)	0
Total number of shares purchased	951,866	2,447,153	982
Average price paid per share (in dollars per share)	$ 101.67	$ 103.41	$ 103.89
2016 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					$ 1,000,000,000
Total number of shares purchased	3,400,001	2,448,135	982
Maximum approximate dollar value of shares that may yet be purchased under the plan	$ 650,000,000	$ 746,800,000	$ 999,900,000

Stockholders' Equity of the C76

Stockholders' Equity of the Company - Perpetual Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	9 Months Ended
	Aug. 31, 2012	Sep. 30, 2017	Dec. 31, 2016	Feb. 28, 2015
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 C77

Stockholders' Equity of the Company - Earnings per Share (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Basic Earnings:
Income attributable to SL Green common stockholders	$ 38,869	$ 34,252	$ 58,442	$ 190,930
Diluted Earnings:
Income attributable to SL Green common stockholders	$ 40,681	$ 35,915	$ 61,149	$ 199,101
Basic Shares:
Weighted average common shares outstanding (shares)	97,783,000	100,233,000	99,431,000	100,140,000
Effect of Dilutive Securities:
Operating Partnership units redeemable for common shares (shares)	4,543,000	4,497,000	4,570,000	4,272,000
Stock-based compensation plans (shares)	244,000	413,000	279,000	349,000
Diluted weighted average common stock outstanding (shares)	102,570,000	105,143,000	104,280,000	104,761,000
Common stock shares excluded from the diluted shares outstanding (shares)	1,175,708	673,298	1,076,695	753,344
Common Stock
Effect of Dilutive Securities:
Redemption of units to common shares	$ 1,812	$ 1,663	$ 2,707	$ 8,171

Partners' Capital of the Oper78

Partners' Capital of the Operating Partnership - Additional Information (Details)	9 Months Ended
	Sep. 30, 2017shares	Dec. 31, 2016shares
Common Stock
Stockholders' Equity
Units outstanding (units)	97,446,000	100,562,000
SL Green Operating Partnership
Stockholders' Equity
Noncontrolling interest in the operating partnership (as a percent)	4.45%	4.16%
Number of units of operating partnership owned by the noncontrolling interest unit holders (units)	4,541,765	4,363,716
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)	97,445,509

Partners' Capital of the Oper79

Partners' Capital of the Operating Partnership - EPS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Denominator
Weighted average common shares outstanding (shares)	97,783,000	100,233,000	99,431,000	100,140,000
Common stock shares excluded from the diluted shares outstanding (shares)	1,175,708	673,298	1,076,695	753,344
SL Green Operating Partnership
Numerator
Net income attributable to SLGOP common unitholders	$ 40,681	$ 35,915	$ 61,149	$ 199,101
Denominator
Weighted average common shares outstanding (shares)	102,326,000	104,730,000	104,001,000	104,412,000
Stock-based compensation plans (shares)	244,000	413,000	279,000	349,000
Diluted weighted average common units outstanding (shares)	102,570,000	105,143,000	104,280,000	104,761,000
Common stock shares excluded from the diluted shares outstanding (shares)	1,175,708	673,298	1,076,695	753,344

Share-based Compensation - Addi

Share-based Compensation - Additional Information (Details) $ / shares in Units, fungible_unit in Millions	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2014shares	Sep. 30, 2017USD ($)unit / sharesunitfungible_unitshares	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)unit / sharesunitfungible_unit$ / sharesshares	Sep. 30, 2016USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015shares	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		$ 1,400,000	$ 1,500,000	$ 5,000,000	$ 4,400,000
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
Exercise price of options granted, low end of the range (in dollars per share) | $ / shares				$ 20.67
Exercise price of options granted, high end of the range (in dollars per share) | $ / shares				$ 128.82
Remaining weighted average contractual life of the options outstanding (in years)				3 years 7 months
Remaining average contractual life of the options exercisable (in years)				2 years 9 months
Total unrecognized compensation cost related to unvested stock awards		10,600,000		$ 10,600,000
Weighted average period for recognition of compensation cost related to unvested stock awards (in years)				1 year 8 months
Weighted average fair value of options granted during the period				$ 3,775,639		$ 8,363,036
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
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense				$ 7,277,054	7,153,966
Total unrecognized compensation cost related to unvested stock awards		$ 13,700,000		$ 13,700,000
Weighted average period for recognition of compensation cost related to unvested stock awards (in years)				1 year 8 months
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				$ 8,400,000		$ 7,600,000
Weighted average fair value of options granted during the period				$ 30,813	$ 10,650,077
Awards granted (in shares) | shares				300	98,800
Awards outstanding (in shares) | shares		3,202,331		3,202,331		3,202,031	3,137,881
LTIP units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of options granted during the period				$ 20,500,000		$ 34,900,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to unvested stock awards		$ 7,100,000		$ 7,100,000
Weighted average period for recognition of compensation cost related to unvested stock awards (in years)				1 year 2 months
Share-based compensation		$ 2,500,000	2,300,000	$ 15,100,000	$ 15,100,000
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		27,030,000
Fungible units per share (in fungible units per share) | unit / shares		3.74		3.74
Shares that may be issued if equal to fungible units (shares) (less than) | shares		27,030,000		27,030,000
Fungible units | fungible_unit		8.7		8.7
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		$ 2,000,000	2,500,000	$ 5,900,000	6,400,000
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		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		1
Award expiration period (in years)				10 years
2014 Outperformance Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense		$ 1,900,000	1,800,000	$ 8,200,000	6,600,000
Capitalized to assets associated with compensation expense related to our long-term compensation plans, restricted stock and stock options				29,200,000
LTIP units earned (in shares) | shares	610,000
Award period (in years)	3 years
Performance period (in years)	3 years
Maximum award to be earned, if performance reaches maximum threshold, first performance period	0.333
Maximum award to be earned, if performance reaches maximum threshold, second performance period	0.667
2014 Outperformance Plan | Vesting on August 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of units vested	50.00%
2014 Outperformance Plan | Vesting on August 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of units vested	50.00%
Deferred Stock Compensation Plan for Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense		$ 100,000	$ 100,000	$ 2,200,000	$ 1,900,000
Maximum percentage of the annual retainer fee, chairman fees and meeting fees that may be deferred by non-employee directors (percent)		100.00%		100.00%
Awards granted (in shares) | shares				11,510
Shares issued (in shares) | shares				9,171
Awards outstanding (in shares) | shares		98,637		98,637
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		101,882		101,882

Share-based Compensation - Stoc

Share-based Compensation - Stock Options and Restricted Stock Activity (Details) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Stock options
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Dividend yield (as a percent)	2.50%		2.37%
Expected life of option (in years)	4 years 4 months 24 days		3 years 8 months 15 days
Risk-free interest rate (as a percent)	1.73%		1.57%
Expected stock price volatility (as a percent)	28.21%		26.76%
Options Outstanding
Balance at beginning of period (in shares)	1,737,213	1,595,007	1,595,007
Granted (in shares)	171,000		445,100
Exercised (in shares)	(146,277)		(192,875)
Lapsed or cancelled (in shares)	(65,300)		(110,019)
Balance at end of period (in shares)	1,696,636		1,737,213
Options exercisable at end of period (in shares)	939,485		748,617
Weighted average fair value of options granted during the period	$ 3,775,639		$ 8,363,036
Weighted Average Exercise Price
Balance at beginning of year (in dollars per share)	$ 98.44	$ 95.52	$ 95.52
Granted (in dollars per share)	105.70		105.86
Exercised (in dollars per share)	84.02		76.90
Lapsed or cancelled (in dollars per share)	122.30		123.86
Balance at end of period (in dollars per share)	99.50		98.44
Options exercisable at end of period (in dollars per share)	$ 91.71		$ 87.72
Restricted Stock Awards
Options Outstanding
Weighted average fair value of options granted during the period	$ 30,813	$ 10,650,077
Summary of restricted stock
Balance at beginning of year (in shares)	3,202,031	3,137,881	3,137,881
Granted (in shares)	300	98,800
Cancelled (in shares)	0	(34,650)
Balance at end of period (in shares)	3,202,331		3,202,031
Vested during the period (in shares)	86,736	83,822

Accumulated Other Comprehensi82

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	$ 7,750,911
Ending Balance	7,184,052
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	22,137
Ending Balance	14,185
SL Green Realty Corp
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Other comprehensive (loss) before reclassifications	(6,749)
Amounts reclassified from accumulated other comprehensive income	(1,203)
Deferred net losses from terminated hedges	3,700	$ 7,100
SL Green Realty Corp | Net unrealized (loss) gain on derivative instruments
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	12,596
Other comprehensive (loss) before reclassifications	(4,669)
Amounts reclassified from accumulated other comprehensive income	1,336
Ending Balance	9,263
SL Green Realty Corp | Net unrealized gain on marketable securities
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	5,520
Other comprehensive (loss) before reclassifications	(1,133)
Amounts reclassified from accumulated other comprehensive income	(3,130)
Ending Balance	1,257
SL Green Realty Corp | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	22,137
Ending Balance	14,185
SL Green Realty Corp | Joint venture | Net unrealized (loss) gain on derivative instruments
Accumulated Other Comprehensive Income (Loss) of the Company [Roll Forward]
Beginning Balance	4,021
Other comprehensive (loss) before reclassifications	(947)
Amounts reclassified from accumulated other comprehensive income	591
Ending Balance	$ 3,665

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value of Financial Instruments
Marketable securities	$ 28,802,000	$ 85,110,000
Interest rate cap and swap agreements (included in other assets)	13,727,000	21,090,000
Debt and preferred equity investments	2,020,739,000	1,640,412,000
Equity method investments	2,045,796,000	1,890,186,000
Additional amount of financing receivables included in other assets	65,600,000	99,500,000
Accrued Interest Payable and Other Liabilities
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in accrued interest payable and other liabilities)		1,000
Carrying Value
Fair Value of Financial Instruments
Debt and preferred equity investments	2,020,739,000	1,640,412,000
Fixed rate debt	5,154,810,000	5,452,084,000
Variable rate debt	1,321,813,000	1,105,585,000
Total	6,476,623,000	6,557,669,000
Fair Value
Fair Value of Financial Instruments
Marketable securities	28,802,000	85,110,000
Total	6,713,093,000	6,832,604,000
Estimated fair value of debt and preferred equity investments, low end of range	2,000,000,000	1,600,000,000
Estimated fair value of debt and preferred equity investments, high end of range	2,200,000,000	1,800,000,000
Level 1
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	0	0
Level 1 | Accrued Interest Payable and Other Liabilities
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in accrued interest payable and other liabilities)		0
Level 2
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	13,727,000	21,090,000
Level 2 | Accrued Interest Payable and Other Liabilities
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in accrued interest payable and other liabilities)		1,000
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 | Accrued Interest Payable and Other Liabilities
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in accrued interest payable and other liabilities)		0
Level 3 | Fair Value
Fair Value of Financial Instruments
Fixed rate debt	5,398,870,000	5,722,494,000
Variable rate debt	1,314,223,000	1,110,110,000
Equity marketable securities
Fair Value of Financial Instruments
Marketable securities	0	48,315,000
Equity marketable securities | Level 1
Fair Value of Financial Instruments
Marketable securities	0	48,315,000
Commercial mortgage-backed securities
Fair Value of Financial Instruments
Marketable securities	28,802,000	36,795,000
Commercial mortgage-backed securities | Level 2
Fair Value of Financial Instruments
Marketable securities	28,802,000	36,795,000
Mezzanine/Jr. Mortgage Loan with an Initial Maturity Date of April 2017
Fair Value of Financial Instruments
Debt and preferred equity investments	250,200,000	$ 0	$ 0
Total fixed rate | Mezzanine/Jr. Mortgage Loan with an Initial Maturity Date of April 2017
Fair Value of Financial Instruments
Notes receivable	$ 250,000,000

Financial Instruments_ Deriva84

Financial Instruments: Derivatives and Hedging (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Financial Instruments: Derivatives and Hedging
Fair Value	$ 13,727,000		$ 13,727,000		$ 21,090,000
Derivative, fair value, net	13,727,000		13,727,000
Gain (loss) from changes in fair value	(100,000)	$ (100,000)	(100,000)	$ 500,000
Fair value of derivatives in a net liability position	0		0
Aggregate termination value	0		0
Estimated current balance held in accumulated other comprehensive loss to be reclassified into earnings within the next 12 months			800,000
Share of joint venture of accumulated other comprehensive loss reclassified into equity in net income from unconsolidated joint ventures within the next 12 months			300,000
Amount of (Loss) Recognized in Other Comprehensive Loss (Effective Portion)	(594,000)	(229,000)	(6,754,000)	(14,104,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	270,000	1,989,000	2,459,000	9,538,000
Amount of (Loss) Gain Recognized into Income (Ineffective Portion)	(44,000)	830,000	(113,000)	(244,000)
Joint venture
Financial Instruments: Derivatives and Hedging
Amount of (Loss) Recognized in Other Comprehensive Loss (Effective Portion)	(290,000)	(222,000)	(1,277,000)	(5,992,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	185,000	547,000	876,000	1,465,000
Amount of (Loss) Gain Recognized into Income (Ineffective Portion)	(48,000)	830,000	(109,000)	(206,000)
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	$ 200,000,000		$ 200,000,000
Strike Rate	0.9375%		0.9375%
Fair Value	$ 105,000		$ 105,000
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	$ 150,000,000		$ 150,000,000
Strike Rate	0.94%		0.94%
Fair Value	$ 78,000		$ 78,000
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	$ 150,000,000		$ 150,000,000
Strike Rate	0.94%		0.94%
Fair Value	$ 78,000		$ 78,000
Interest Rate Cap Expiring in September 2017
Financial Instruments: Derivatives and Hedging
Notional Value	$ 137,500,000		$ 137,500,000
Strike Rate	4.00%		4.00%
Fair Value	$ 4,000		$ 4,000
Interest Rate Swap Expiring in July 2023
Financial Instruments: Derivatives and Hedging
Notional Value	$ 200,000,000		$ 200,000,000
Strike Rate	1.131%		1.131%
Fair Value	$ 8,998,000		$ 8,998,000
Interest Rate Swap Expiring in July 2023
Financial Instruments: Derivatives and Hedging
Notional Value	$ 100,000,000		$ 100,000,000
Strike Rate	1.161%		1.161%
Fair Value	$ 4,335,000		$ 4,335,000
Interest Rate Swap Expiring in November 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 100,000,000		$ 100,000,000
Strike Rate	2.287%		2.287%
Fair Value	$ 129,000		$ 129,000
Interest Rate Swaps/Caps
Financial Instruments: Derivatives and Hedging
Amount of (Loss) Recognized in Other Comprehensive Loss (Effective Portion)	(304,000)	(7,000)	(5,477,000)	(8,112,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	85,000	1,442,000	1,583,000	8,073,000
Amount of (Loss) Gain Recognized into Income (Ineffective Portion)	$ 4,000	$ 0	$ (4,000)	$ (38,000)

Commitments and Contingencies85

Commitments and Contingencies (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Initial term of non cancellable operating leases, minimum (in years)	1 year
Capital lease
Remaining 2,017	$ 597
2,018	2,387
2,019	2,411
2,020	2,620
2,021	2,794
Thereafter	822,688
Total minimum lease payments	833,497
Amount representing interest	(790,837)
Capital lease obligations	42,660
Non-cancellable operating leases
Remaining 2,017	7,763
2,018	31,049
2,019	31,066
2,020	31,436
2,021	31,628
Thereafter	732,724
Total minimum lease payments	$ 865,666

Segment Information - Additiona

Segment Information - Additional Information (Details) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)segment	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Segment information
Number of reportable segments (segment) | segment				2
Total revenues		$ 374,600	$ 416,681	$ 1,150,131	$ 1,489,739
Net income (loss) before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain on sale of real estate, net, depreciable real estate reserves, and gain on sale of investment in marketable securities		44,765	42,721	131,898	(18,927)
Total assets	[1]	15,109,870		15,109,870		$ 15,857,787
Marketing, general and administrative		23,963	25,458	72,362	73,974
Operating Segments | Real Estate Segment
Segment information
Total revenues		326,780	341,285	1,001,390	1,315,392
Net income (loss) before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain on sale of real estate, net, depreciable real estate reserves, and gain on sale of investment in marketable securities		4,873	(32,731)	(504)	(187,222)
Total assets		12,939,363		12,939,363		13,868,672
Operating Segments | Debt and Preferred Equity Segment
Segment information
Total revenues		47,820	75,396	148,741	174,347
Net income (loss) before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain on sale of real estate, net, depreciable real estate reserves, and gain on sale of investment in marketable securities		39,892	$ 75,452	132,402	$ 168,295
Total assets		$ 2,170,507		$ 2,170,507		$ 1,989,115
[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: $384.3 million and $412.3 million of land, $1.4 billion and $1.5 billion of building and improvements, $2.0 million and $2.0 million of building and leasehold improvements, $47.4 million and $47.4 million of properties under capital lease, $323.3 million and $327.2 million of accumulated depreciation, $235.4 million and $244.2 million of other assets included in other line items, $627.8 million and $621.8 million of real estate debt, net, $2.5 million and $2.2 million of accrued interest payable, $42.7 million and $42.1 million of capital lease obligations, and $58.5 million and $73.3 million of other liabilities included in other line items as of September 30, 2017 and December 31, 2016, respectively.

Segment Information - Schedule

Segment Information - Schedule of Reconciliation of Income from Continuing Operations to Net Income Attributable to SL Green Common Stockholders (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reconciliation of income from continuing operations to net income attributable to SL Green common stockholders
Net income (loss) before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain on sale of real estate, net, depreciable real estate reserves, and gain on sale of investment in marketable securities	$ 44,765	$ 42,721	$ 131,898	$ (18,927)
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	1,030	225	16,166	43,588
Gain (loss) on sale of real estate, net	0	397	(3,256)	210,750
Depreciable real estate reserves	0	0	(85,336)	(10,387)
Gain (loss) on sale of investment in marketable securities	0	0	3,262	(83)
Net income	$ 45,795	$ 43,343	$ 62,734	$ 224,941

Uncategorized Items - slg-20170

Label	Element	Value
Stock Issued to Joint Venture	slg_StockIssuedtoJointVenture	$ 114,049,000