Actuarial Assumptions Used to Determine Benefit Obligation and Net Periodic Service Cost (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.40%	3.25%	4.25%
Gentherm GmbH
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.21%	1.95%
Expected long term rate of return on plan assets	3.70%	3.80%