Revenues (Detail) - USD ($) $ 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
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 3,706	$ 3,578	$ 3,689	$ 3,513	$ 3,559	$ 3,460	$ 3,484	$ 3,293	$ 14,486	$ 13,796	$ 12,784
Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									14,218	13,540	12,518
Total segment | International Operations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									2,761	2,518	2,149
Total segment | North American Full-Service Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									8,825	8,323	7,978
Total segment | North American Limited-Service Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									3,193	2,962	2,583
Total segment | International
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									2,200	2,255	1,957
Other unallocated corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									$ 268	$ 256	$ 266