Partners' Capital of the Operating Partnership (Details)	Sep. 30, 2014	Dec. 31, 2013
Common Stock
Stockholders' Equity
Shares outstanding (shares)	95,945,000	94,993,000
SL Green Operating Partnership
Stockholders' Equity
Noncontrolling interest in the operating partnership (as a percent)	3.75%	2.96%
Number of units of operating partnership owned by the noncontrolling interest unit holders (shares)	3,735,478	2,902,317
SL Green Operating Partnership | Common Stock
Stockholders' Equity
Shares outstanding (shares)	95,944,861
Series I Preferred Units | SL Green Operating Partnership
Stockholders' Equity
Shares outstanding (shares)	9,200,000