Partners' Capital of the Operating Partnership (Details) - shares	Jun. 30, 2017	Dec. 31, 2016
Common Stock
Stockholders' Equity
Units outstanding (units)	98,367,000	100,562,000
SL Green Operating Partnership
Stockholders' Equity
Noncontrolling interest in the operating partnership (as a percent)	4.43%	4.16%
Number of units of operating partnership owned by the noncontrolling interest unit holders (units)	4,561,513	4,363,716
SL Green Operating Partnership | Series I Preferred Units
Stockholders' Equity
Units outstanding (units)	9,200,000
SL Green Operating Partnership | Common Stock
Stockholders' Equity
Units outstanding (units)	98,366,984