Relationship with KAR and Related Entities (Details)	12 Months Ended
Jan. 01, 2023
Related Party Transactions [Abstract]
Non-compete period	5 years
Services period	2 years

Separation And Distribution Agreement, Non-Compete Period

No definition available.

Name:	iaa_SeparationAndDistributionAgreementNonCompetePeriod
Namespace Prefix:	iaa_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration