Segment Information (Narrative) (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Assets under vehicle programs	$ 12,796	$ 9,173
Americas
Segment Reporting Information [Line Items]
Assets under vehicle programs	10,300	7,200
International
Segment Reporting Information [Line Items]
Assets under vehicle programs	$ 2,500	$ 2,000