Noncontrolling Interests on the Company's Consolidated Financial Statements - Additional Information (Details) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($) $ / shares shares	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2023 shares
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Redemption and conversion of common units | $	$ (5,674)
Net income (loss) | $	901	$ (2,337)
Accumulated other comprehensive income (loss) allocation | $	$ 1,622	(1,851)
SL Green Operating Partnership
Organization
Number of units of operating partnership owned by the noncontrolling interest unit holders (shares)	4,417,247			3,949,448
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Redemption and conversion of common units | $	$ (5,674)
Accumulated other comprehensive income (loss) allocation | $	$ 1,622	(1,851)
SL Green Operating Partnership | Series A
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)	109,161
Number of Units Issued (in shares)	109,161
Number of Units Outstanding (in shares)	109,161
Annual Dividend Per Unit (in dollars per share) | $ / shares	$ 50.0000
Liquidation Preference Per Unit (in dollars per share) | $ / shares	1,000
Conversion Price Per Unit (in dollars per share) | $ / shares	$ 0
Number of company common stock issued on conversion of Series B preferred units	6.71348
SL Green Operating Partnership | Series F
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate	7.00%
Number of Units Authorized (in shares)	60
Number of Units Issued (in shares)	60
Number of Units Outstanding (in shares)	60
Annual Dividend Per Unit (in dollars per share) | $ / shares	$ 70.0000
Liquidation Preference Per Unit (in dollars per share) | $ / shares	1,000
Conversion Price Per Unit (in dollars per share) | $ / shares	$ 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
Number of Units Issued (in shares)	563,954
Number of Units Outstanding (in shares)	341,677
Annual Dividend Per Unit (in dollars per share) | $ / shares	$ 0.8750
Liquidation Preference Per Unit (in dollars per share) | $ / shares	25.00
Conversion Price Per Unit (in dollars per share) | $ / shares	$ 134.67
SL Green Operating Partnership | Series L
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate	4.00%
Number of Units Authorized (in shares)	500,000
Number of Units Issued (in shares)	378,634
Number of Units Outstanding (in shares)	372,634
Annual Dividend Per Unit (in dollars per share) | $ / shares	$ 1.0000
Liquidation Preference Per Unit (in dollars per share) | $ / shares	25.00
Conversion Price Per Unit (in dollars per share) | $ / shares	$ 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
Number of Units Issued (in shares)	400,000
Number of Units Outstanding (in shares)	400,000
Annual Dividend Per Unit (in dollars per share) | $ / shares	$ 0.8750
Liquidation Preference Per Unit (in dollars per share) | $ / shares	25.00
Conversion Price Per Unit (in dollars per share) | $ / shares	$ 154.89
SL Green Operating Partnership | Series S
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate	4.00%
Number of Units Authorized (in shares)	1,077,280
Number of Units Issued (in shares)	1,077,280
Number of Units Outstanding (in shares)	1,077,280
Annual Dividend Per Unit (in dollars per share) | $ / shares	$ 1.0000
Liquidation Preference Per Unit (in dollars per share) | $ / shares	25.00
Conversion Price Per Unit (in dollars per share) | $ / shares	$ 0
SL Green Operating Partnership | Series V
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Stated Distribution Rate	5.00%
Number of Units Authorized (in shares)	40,000
Number of Units Issued (in shares)	40,000
Number of Units Outstanding (in shares)	40,000
Annual Dividend Per Unit (in dollars per share) | $ / shares	$ 1.2500
Liquidation Preference Per Unit (in dollars per share) | $ / shares	25.00
Conversion Price Per Unit (in dollars per share) | $ / shares	$ 0
SL Green Operating Partnership | Series W
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Number of Units Authorized (in shares)	1
Number of Units Issued (in shares)	1
Number of Units Outstanding (in shares)	1
Preferred stock, dividend, multiplier per common unit distribution	1,350
SL Green Operating Partnership | Series B Preferred Stock
Rollforward analysis of the activity relating to the noncontrolling interests in the operating partnership
Convertible preferred stock, shares issued upon conversion (in shares)	1
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
Distributions | $	(3,609)		$ (14,779)
Issuance of common units | $	6,025		25,365
Redemption and conversion of common units | $	(13,596)		(18,589)
Net income (loss) | $	901		(37,465)
Accumulated other comprehensive income (loss) allocation | $	1,622		(1,960)
Fair value adjustment | $	42,841		15,486
Balance at end of period | $	$ 272,235		$ 269,993
Operating Partnership | SL Green Operating Partnership
Organization
Noncontrolling interest in the operating partnership (as a percent)	6.38%			5.75%