Consolidated Statements of Income (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Product revenues	$ 811,300	$ 662,082	$ 554,979
Cost of sales	569,618	487,320	413,052
Gross margin	241,682	174,762	141,927
Operating costs and expenses:
Research and development expenses	66,411	52,197	43,189
Reimbursed research and development expenses	(8,885)	(2,324)	(2,239)
Net research and development expenses	57,526	49,873	40,950
Acquisition transaction expenses	1,075	2,414
Selling, general and administrative expenses	84,647	72,091	64,321
Total operating costs and expenses	143,248	124,378	105,271
Operating income	98,434	50,384	36,656
Interest expense	(3,262)	(3,543)	(4,136)
Debt retirement expense	(1,370)
Revaluation of derivatives (loss) gain	(518)	1,006	(2,292)
Foreign currency (loss) gain	(218)	(2,228)	2,201
Gain (loss) from equity investment	785	436	(82)
Other income	370	175	325
Earnings before income tax	94,221	46,230	32,672
Income tax expense	24,102	11,097	8,351
Net income	70,119	35,133	24,321
Income attributable to non-controlling interest		(1,313)	(6,449)
Net income attributable to Gentherm Incorporated	70,119	33,820	17,872
Convertible preferred stock dividends		(1,622)	(6,711)
Net income attributable to common shareholders	$ 70,119	$ 32,198	$ 11,161
Basic earnings per share	$ 1.98	$ 0.96	$ 0.39
Diluted earnings per share	$ 1.95	$ 0.94	$ 0.39
Weighted average number of shares—basic	35,411,608	33,652,646	28,352,864
Weighted average number of shares—diluted	36,049,331	34,123,641	28,862,463