Business Segments - Segment Revenues (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 5,049	$ 5,078	$ 15,401	$ 15,201
Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	4,834	4,813	14,815	14,500
Other unallocated corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	215	265	586	701
North American Full-Service | Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	3,123	3,096	9,778	9,613
North American Limited-Service | Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	875	863	2,524	2,440
Asia Pacific | Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	275	263	818	756
Other International | Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 561	$ 591	$ 1,695	$ 1,691