Industry Segments (Details) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Segment	Jun. 30, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reportable operating segments | Segment				2
Net sales	[1]	$ 312,729	$ 288,977	$ 595,107	$ 527,888
Operating Income		29,669	31,844	55,188	51,863
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales		0	0	0	0
Engine Management [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net sales	[1]	223,349	198,848	434,663	379,529
Operating Income		26,489	30,548	53,774	54,752
Engine Management [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales		5,831	5,817	13,143	10,689
Temperature Control [Member] | Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net sales	[1]	87,391	87,503	157,681	144,269
Operating Income		8,262	5,647	12,229	7,814
Temperature Control [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales		2,095	2,121	4,124	3,715
All Other [Member]
Segment Reporting Information [Line Items]
Net sales	[1]	1,989	2,626	2,763	4,090
Operating Income		(5,082)	(4,351)	(10,815)	(10,703)
All Other [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales		$ (7,926)	$ (7,938)	$ (17,267)	$ (14,404)

[1] Segment net sales includes intersegment sales in our Engine Management and Temperature Control segments.