Revenues and Long-Lived Assets by Geographical Area (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 1,620	$ 5,469	$ 5,524
Property and equipment, net	9,416	9,671	9,760
United States
Segment Reporting Information [Line Items]
Revenues	1,600	5,381	5,417
Property and equipment, net	9,331	9,570	9,651
Brazil
Segment Reporting Information [Line Items]
Revenues	7	23	19
Property and equipment, net	34	45	49
Canada
Segment Reporting Information [Line Items]
Revenues	13	65	67
Property and equipment, net	$ 51	$ 56	60
Mexico
Segment Reporting Information [Line Items]
Revenues			$ 21