Revenues and Long-Lived Assets by Geographical Area (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 1,346	$ 1,348
Property and equipment, net	10,650		$ 9,692
United States
Segment Reporting Information [Line Items]
Revenues	1,320	1,317
Property and equipment, net	10,509		9,548
Australia
Segment Reporting Information [Line Items]
Revenues		9
Brazil
Segment Reporting Information [Line Items]
Revenues	5	5
Property and equipment, net	59		59
Canada
Segment Reporting Information [Line Items]
Revenues	14	10
Property and equipment, net	68		71
Mexico
Segment Reporting Information [Line Items]
Revenues	7	$ 7
Property and equipment, net	$ 14		$ 14