Supplemental Information for the Consolidated Statements of Cash Flows - Noncash Activity (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Supplemental Information For Statements of Cash Flows [Abstract]
Subvention receivable from GM	$ 452	$ 360	$ 508
Commercial loan funding payable to GM	$ 94	$ 100	$ 55

he increase (decrease) in the subvention receivable from a related party.

No definition available.

Name:	acf_IncreaseDecreaseInRelatedPartySubventionReceivable
Namespace Prefix:	acf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration