Pension and Other Post Retirement Benefit Plans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) Payment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Vesting period	6 years
Discount rate for net periodic service cost	3.25%	4.25%	3.25%
Discount rate for benefit obligation	3.40%	3.25%	4.25%
Insurance policy value	$ 1,993,000	$ 2,056,000
Tax (expense) benefit recognized in other comprehensive income	(23,000)	121,000	$ 0
Pretax unrecognized actuarial losses recorded in accumulated other comprehensive income (loss)	266,000	328,000
Expected pretax unrecognized actuarial losses recorded in accumulated other comprehensive income (loss ) in next fiscal year	0
Contributions to 401(k) plan	$ 959,000	$ 543,000	191,000
Gentherm GmbH
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligation	2.21%	1.95%
Tax (expense) benefit recognized in other comprehensive income	$ (211,000)	$ 559,000	$ 18,000
Pretax unrecognized actuarial losses recorded in accumulated other comprehensive income (loss)	1,821,000	2,267,000
Expected pretax unrecognized actuarial losses recorded in accumulated other comprehensive income (loss ) in next fiscal year	47,000
Pension benefit obligation	3,647,000
Underfunded defined benefit plan	3,647,000	4,505,000
Defined benefit plan, expected employer contribution in next fiscal year	257,000
Gentherm GmbH | Accrued Liabilities
Defined Benefit Plan Disclosure [Line Items]
Portion of the net benefit obligation payable	0	$ 274,000
Chief Executive Officer
Defined Benefit Plan Disclosure [Line Items]
Annual retirement payment	$ 300,000,000
Number of expected annual retirement benefit payments | Payment	15
Annual retirement benefit payments, earliest date	Jan. 01, 2018