Business Segments - Summary of Operating Results by Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue:
Total revenue	$ 604	$ 785
Operating profit (loss):
Total operating profit (loss)	(333)	23
United States [Member]
Revenue:
Total revenue	441	600
Operating profit (loss):
Total operating profit (loss)	(204)	19
Canada [Member]
Revenue:
Total revenue	78	86
Operating profit (loss):
Total operating profit (loss)	(58)	2
International [Member]
Revenue:
Total revenue	85	99
Operating profit (loss):
Total operating profit (loss)	$ (71)	$ 2