Financial Instruments - Summary of Receivables Factored and Availability Under Receivables Factoring Agreements (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Receivables factored and outstanding	$ 22,372	$ 19,108
Amount available under the credit limit	1,169	5,034
Collective factoring limit	$ 23,541	$ 24,142

Maximum limits for accounts receivable factoring arrangements.

No definition available.

Name:	thrm_MaximumLimitsForAccountsReceivableFactoringArrangements
Namespace Prefix:	thrm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant