Quarterly Results (Unaudited) - Schedule of Quarterly Financial Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenues	$ 1,433	$ 1,434	$ 1,481	$ 1,415	$ 1,493	$ 1,493	$ 1,539	$ 1,458	$ 5,763	$ 5,983	$ 6,115
Costs and expenses	1,242	1,234	1,285	1,262	1,251	1,283	1,302	1,264	5,023	5,100	5,190
Income from continuing operations	166	88	136	99	245	109	153	136	489	643	565
Discontinued operations					(11)			1		(10)
Net income attributable to Starwood	$ 166	$ 88	$ 136	$ 99	$ 234	$ 109	$ 153	$ 137	$ 489	$ 633	$ 635
Basic —
Income from continuing operations	$ 0.99	$ 0.53	$ 0.80	$ 0.59	$ 1.41	$ 0.60	$ 0.81	$ 0.71	$ 2.90	$ 3.49	$ 2.96
Discontinued operations					(0.07)			0.01		(0.06)	0.37
Net income	0.99	0.53	0.80	0.59	1.34	0.60	0.81	0.72	2.90	3.43	3.33
Diluted —
Income from continuing operations	0.98	0.53	0.79	0.58	1.40	0.59	0.80	0.71	2.88	3.46	2.92
Discontinued operations					(0.07)			0.01		(0.06)	0.36
Net income	$ 0.98	$ 0.53	$ 0.79	$ 0.58	$ 1.33	$ 0.59	$ 0.80	$ 0.72	$ 2.88	$ 3.40	$ 3.28