Earnings per Share - Reconciliation of Basic Earnings per Share to Diluted Earnings per Share for Income from Continuing Operations (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Basic earnings from continuing operations attributable to Starwood's common stockholders	$ 245	$ 109	$ 153	$ 136	$ 128	$ 157	$ 137	$ 143	$ 643	$ 565	$ 470
Employee options and restricted stock awards									0	0	0
Diluted earnings from continuing operations attributable to Starwood's common stockholders									$ 643	$ 565	$ 470
Basic earnings from continuing operations attributable to Starwood's common stockholders									185	191	193
Employee options and restricted stock awards, Shares									1	2	4
Diluted earnings from continuing operations attributable to Starwood's common stockholders									186	193	197
Basic earnings from continuing operations attributable to Starwood's common stockholders, Per Share	$ 1.41	$ 0.60	$ 0.81	$ 0.71	$ 0.68	$ 0.82	$ 0.72	$ 0.74	$ 3.49	$ 2.96	$ 2.44
Diluted earnings from continuing operations attributable to Starwood's common stockholders, Per Share	$ 1.40	$ 0.59	$ 0.80	$ 0.71	$ 0.67	$ 0.81	$ 0.71	$ 0.73	$ 3.46	$ 2.92	$ 2.39