Stockholders' Equity - Equity Attributable to Starwood's Stockholders (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Beginning Balance	$ 3,345		$ 3,142
Net income	138	122	350	250
Equity compensation activity and other	41		93
Share repurchases	(8)		(56)
Other comprehensive income (loss)	(35)	(49)	(48)	(10)
Ending Balance	3,481		3,481
Common Shares [Member]
Beginning Balance	2		2
Net income
Equity compensation activity and other
Share repurchases
Other comprehensive income (loss)
Ending Balance	2		2
Additional Paid-in Capital [Member]
Beginning Balance	820		816
Net income
Equity compensation activity and other	41		93
Share repurchases	(8)		(56)
Other comprehensive income (loss)
Ending Balance	853		853
Accumulated Other Comprehensive Loss [Member]
Beginning Balance	(350)		(338)
Net income
Equity compensation activity and other
Share repurchases
Other comprehensive income (loss)	(36)		(48)
Ending Balance	(386)		(386)
Retained Earnings [Member]
Beginning Balance	2,870		2,657
Net income	137		350
Equity compensation activity and other
Share repurchases
Other comprehensive income (loss)
Ending Balance	3,007		3,007
Equity Attributable to Noncontrolling Interests [Member]
Beginning Balance	3		5
Net income	1
Equity compensation activity and other
Share repurchases
Other comprehensive income (loss)	1
Ending Balance	$ 5		$ 5