Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt and preferred equity investments, discount and deferred origination fees	$ 12,031	$ 14,562
Allowance for loan and lease losses, real estate	$ 19,010	$ 1,750
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)	74,095,000	80,257,000
Common stock, shares outstanding (in shares)	74,095,000	80,257,000
Treasury stock, shares (in shares)	1,055,000	1,055,000
Land and land interests	$ 1,639,118	$ 1,751,544
Building and improvements	5,483,155	5,154,990
Building leasehold and improvements	1,442,251	1,433,793
Right of use asset - financing leases	75,711	47,445
Accumulated depreciation	2,260,247	2,060,560
Other assets	514,873	332,801
Mortgages and other loans payable, net	2,391,744	2,183,253
Accrued interest payable	23,438	22,148
Lease liability - financing leases	174,983	44,448
Other liabilities	$ 306,077	$ 177,080
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	$ 12,031	$ 14,562
Allowance for loan and lease losses, real estate	$ 19,010	$ 1,750
Limited partner interests in Operating Partnership, limited partner common units outstanding (shares)	4,027,000	4,196,000
SL Green partner's capital, general partner common units outstanding (shares)	771,000	834,000
SL Green partners' capital, limited partner common units outstanding (shares)	72,269,000	78,368,000
Land and land interests	$ 1,639,118	$ 1,751,544
Building and improvements	5,483,155	5,154,990
Building leasehold and improvements	1,442,251	1,433,793
Right of use asset - financing leases	75,711	47,445
Accumulated depreciation	2,260,247	2,060,560
Other assets	514,873	332,801
Mortgages and other loans payable, net	2,391,744	2,183,253
Accrued interest payable	23,438	22,148
Lease liability - financing leases	174,983	44,448
Other liabilities	$ 306,077	$ 177,080
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
Consolidated VIEs
Land and land interests	$ 375,900	$ 205,200
Building and improvements	1,400,000	481,900
Building leasehold and improvements	2,000	2,000
Right of use asset - financing leases	61,700	61,700
Accumulated depreciation	296,300	17,600
Other assets	322,800	169,500
Mortgages and other loans payable, net	510,700	457,100
Accrued interest payable	1,100	1,200
Lease liability - financing leases	58,400	57,700
Other liabilities	48,900	43,700
Consolidated VIEs | SL Green Operating Partnership
Land and land interests	375,900	205,200
Building and improvements	1,400,000	481,900
Building leasehold and improvements	2,000	2,000
Right of use asset - financing leases	61,700	61,700
Accumulated depreciation	296,300	17,600
Other assets	322,800	169,500
Mortgages and other loans payable, net	510,700	457,100
Accrued interest payable	1,100	1,200
Lease liability - financing leases	58,400	57,700
Other liabilities	$ 48,900	$ 43,700