Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt and preferred equity investments, discount and deferred origination fees	$ 9,817	$ 11,232
Allowance for loan and lease losses, real estate	$ 13,213	$ 13,213
Preferred stock, par value (in dollars per share)	$ 0.01
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	160,000,000	160,000,000
Common stock, shares issued (in shares)	70,380,000	69,534,000
Common stock, shares outstanding (in shares)	70,380,000	69,534,000
Treasury stock, shares (in shares)	1,026,000	1,026,000
Land and land interests	$ 1,445,199	$ 1,315,832
Building and improvements	4,096,930	4,168,193
Building leasehold and improvements	1,730,418	1,448,134
Right of use asset - financing leases	55,711	55,711
Accumulated depreciation	2,004,945	1,956,077
Other assets	445,635	448,213
Mortgages and other loans payable, net	1,848,701	1,979,972
Accrued interest payable	22,796	14,825
Lease liability - financing leases	152,622	152,521
Other liabilities	$ 267,908	$ 302,798
Series I Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference (in dollars per share)	$ 25.00	$ 25.00
Preferred stock, shares issued (in shares)	9,200,000	9,200,000
Preferred stock, shares outstanding (in shares)	9,200,000	9,200,000
SL Green Operating Partnership
Debt and preferred equity investments, discount and deferred origination fees	$ 9,817	$ 11,232
Allowance for loan and lease losses, real estate	$ 13,213	$ 13,213
Limited partner interests in Operating Partnership, limited partner common units outstanding (shares)	4,156,000	3,939,000
SL Green partner's capital, general partner common units outstanding (shares)	735,000	724,000
SL Green partners' capital, limited partner common units outstanding (shares)	68,619,000	67,784,000
Land and land interests	$ 1,445,199	$ 1,315,832
Building and improvements	4,096,930	4,168,193
Building leasehold and improvements	1,730,418	1,448,134
Right of use asset - financing leases	55,711	55,711
Accumulated depreciation	2,004,945	1,956,077
Other assets	445,635	448,213
Mortgages and other loans payable, net	1,848,701	1,979,972
Accrued interest payable	22,796	14,825
Lease liability - financing leases	152,622	152,521
Other liabilities	$ 267,908	$ 302,798
SL Green Operating Partnership | Series I Preferred Stock
Preferred units, liquidation preference (in dollars per share)	$ 25.00	$ 25.00
Preferred units, shares issued (in shares)	9,200,000	9,200,000
Preferred units, shares outstanding (in shares)	9,200,000	9,200,000
Variable Interest Entity, Primary Beneficiary
Land and land interests	$ 179,600	$ 41,200
Building and improvements	282,300	57,900
Building leasehold and improvements	2,000	2,000
Right of use asset - financing leases	53,200	37,800
Accumulated depreciation	16,400	10,300
Other assets	297,100	289,500
Mortgages and other loans payable, net	368,600	94,000
Accrued interest payable	900	700
Lease liability - financing leases	45,300	29,900
Other liabilities	$ 31,200	$ 56,600