Variable Interest Entities - Additional Information (Details) - USD ($) $ in Billions	Mar. 31, 2025	Mar. 31, 2024
Variable Interest Entities [Abstract]
Securities retained by TMCC	$ 1.6	$ 1.6

The amount of securities retained by the reporting entity in the consolidated Variable Interest Entity's debt obligations collateralized by finance receivables.

No definition available.

Name:	ck0000834071_VariableInterestEntityConsolidatedCarryingAmountSecuredDebtAmountRetainedByReportingEntity
Namespace Prefix:	ck0000834071_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant