Stockholders' Equity of the Company - Additional Information (Details) - $ / shares	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Authorized capital stock (in 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 (in dollars per share)	$ 0.01
Excess shares issued (shares)	0
Common Stock
Class of Stock [Line Items]
Shares, outstanding (in shares)	79,202,000	83,684,000	92,803,000	100,562,000
Common Stock | SL Green Operating Partnership
Class of Stock [Line Items]
Shares, outstanding (in shares)	79,202,322