Segment Information (Narrative) (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Assets under vehicle programs	$ 10,135	$ 9,173
Americas
Segment Reporting Information [Line Items]
Assets under vehicle programs	8,200	7,200
International
Segment Reporting Information [Line Items]
Assets under vehicle programs	$ 1,900	$ 2,000