Noncontrolling Interests on the Company's Consolidated Financial Statements - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Issuance of common units			$ 1,823
Redemption and conversion of common units			(5,674)
Net income (loss)		$ (1,574)	(166)	$ (27,493)
Accumulated other comprehensive income (loss) allocation	$ (4,717)	771	$ (3,097)	1,425
SL Green Operating Partnership
Organization
Number of units of operating partnership owned by the noncontrolling interest unit holders (shares)	4,474,406		4,474,406		3,949,448
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Issuance of common units			$ 1,823
Redemption and conversion of common units			(5,674)
Net income (loss)	$ (914)		(166)
Accumulated other comprehensive income (loss) allocation	$ (4,717)	$ 771	$ (3,097)	1,425	$ (1,960)
SL Green Operating Partnership | Series A
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate			6.00%
Number of units authorized (in shares)	109,161		109,161
Number of units issued (in shares)	109,161		109,161
Number of units outstanding (in shares)	109,161		109,161
Annual dividend per unit (in dollars per share)			$ 60.0000
Liquidation preference per unit (in dollars per share)	$ 1,000		1,000
Conversion price per unit (in dollars per share)	$ 0		$ 0
SL Green Operating Partnership | Series F
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate			7.00%
Number of units authorized (in shares)	60		60
Number of units issued (in shares)	60		60
Number of units outstanding (in shares)	60		60
Annual dividend per unit (in dollars per share)			$ 70.0000
Liquidation preference per unit (in dollars per share)	$ 1,000		1,000
Conversion price per unit (in dollars per share)	$ 29.12		$ 29.12
SL Green Operating Partnership | Series K
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate			3.50%
Number of units authorized (in shares)	700,000		700,000
Number of units issued (in shares)	563,954		563,954
Number of units outstanding (in shares)	341,677		341,677
Annual dividend per unit (in dollars per share)			$ 0.8750
Liquidation preference per unit (in dollars per share)	$ 25.00		25.00
Conversion price per unit (in dollars per share)	$ 134.67		$ 134.67
SL Green Operating Partnership | Series L
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate			4.00%
Number of units authorized (in shares)	500,000		500,000
Number of units issued (in shares)	378,634		378,634
Number of units outstanding (in shares)	372,634		372,634
Annual dividend per unit (in dollars per share)			$ 1.0000
Liquidation preference per unit (in dollars per share)	$ 25.00		25.00
Conversion price per unit (in dollars per share)	$ 0		$ 0
SL Green Operating Partnership | Series R
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate			3.50%
Number of units authorized (in shares)	400,000		400,000
Number of units issued (in shares)	400,000		400,000
Number of units outstanding (in shares)	400,000		400,000
Annual dividend per unit (in dollars per share)			$ 0.8750
Liquidation preference per unit (in dollars per share)	$ 25.00		25.00
Conversion price per unit (in dollars per share)	$ 154.89		$ 154.89
SL Green Operating Partnership | Series S
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate			4.00%
Number of units authorized (in shares)	1,077,280		1,077,280
Number of units issued (in shares)	1,077,280		1,077,280
Number of units outstanding (in shares)	1,077,280		1,077,280
Annual dividend per unit (in dollars per share)			$ 1.0000
Liquidation preference per unit (in dollars per share)	$ 25.00		25.00
Conversion price per unit (in dollars per share)	$ 0		$ 0
SL Green Operating Partnership | Series V
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate			5.00%
Number of units authorized (in shares)	40,000		40,000
Number of units issued (in shares)	40,000		40,000
Number of units outstanding (in shares)	40,000		40,000
Annual dividend per unit (in dollars per share)			$ 1.2500
Liquidation preference per unit (in dollars per share)	$ 25.00		25.00
Conversion price per unit (in dollars per share)	$ 0		$ 0
SL Green Operating Partnership | Series W
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of units authorized (in shares)	1		1
Number of units issued (in shares)	1		1
Number of units outstanding (in shares)	1		1
Preferred stock, dividend, multiplier per common unit distribution			1,350
Partnership Interest
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Balance at beginning of period			$ 238,051	$ 269,993	269,993
Distributions			(10,545)		(14,779)
Issuance of common units			13,927		25,365
Redemption and conversion of common units			(21,977)		(18,589)
Net income (loss)			(166)		(37,465)
Fair value adjustment			77,400		15,486
Balance at end of period	$ 293,593		$ 293,593		$ 238,051
Operating Partnership | SL Green Operating Partnership
Organization
Noncontrolling interest in the operating partnership (as a percent)	6.42%		6.42%		5.75%