Financial Instruments - Summary of Receivables Factored and Availability Under Receivables Factoring Agreements (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Receivables factored and outstanding	$ 16,510	$ 18,532
Amount available under the credit limit	7,425	5,891
Collective factoring limit	$ 23,935	$ 24,423

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