Business Segments - Segment Revenues (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 5,346	$ 5,211	$ 10,352	$ 10,123
Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	5,119	4,953	9,981	9,687
Other unallocated corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	227	258	371	436
North American Full-Service | Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	3,356	3,277	6,655	6,517
North American Limited-Service | Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	888	836	1,649	1,577
Asia Pacific | Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	268	252	543	493
Other International | Total segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 607	$ 588	$ 1,134	$ 1,100