Earnings per Share - Reconciliation of Basic Earnings per Share to Diluted Earnings per Share for Income (Loss) from Continuing Operations (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ (35)	$ 118	$ 38	$ 193
Income (loss) from discontinued operations	(228)	18	(211)	42
Net income (loss) attributable to Starwood	$ (263)	$ 136	$ (173)	$ 235
Weighted average common shares for basic earnings per share	168	169	168	170
Effect of dilutive stock options and restricted stock awards		1	1	1
Weighted average common shares for diluted earnings per share	168	170	169	171
Basic earnings (losses) per share:
Continuing operations	$ (0.20)	$ 0.69	$ 0.23	$ 1.13
Discontinued operations	(1.36)	0.11	(1.26)	0.25
Net income (loss)	(1.56)	0.80	(1.03)	1.38
Diluted earnings (losses) per share:
Continuing operations	(0.20)	0.69	0.23	1.13
Discontinued operations	(1.36)	0.10	(1.25)	0.24
Net income (loss)	$ (1.56)	$ 0.79	$ (1.02)	$ 1.37