Industry Segment and Geographic Data, Reportable Segments (Details) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) Segment		Dec. 31, 2017 USD ($)		Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reportable operating segments | Segment										2
Financial information for reportable segment [Abstract]
Net sales		$ 246,970	$ 296,619	$ 286,636	$ 261,826	$ 239,978	$ 281,058	$ 312,729	$ 282,378	$ 1,092,051	[1],[2]	$ 1,116,143	[1],[2],[3],[4]	$ 1,058,482	[1],[2],[3],[4]
Depreciation and amortization										24,104		23,916		20,457
Operating income (loss)										81,268		97,521		98,789
Investment in unconsolidated affiliates		32,469				31,184				32,469		31,184		19,924
Capital expenditures										20,141		24,442		20,921
Total assets		843,132				787,567				843,132		787,567		768,697
Intersegment Eliminations [Member]
Financial information for reportable segment [Abstract]
Net sales	[2]									0		0	[3]	0	[3]
Engine Management [Member] | Reportable Segments [Member]
Financial information for reportable segment [Abstract]
Net sales	[2]									803,487		829,413	[3]	765,539	[3]
Depreciation and amortization										17,858		17,981		15,008
Operating income (loss)										84,844		97,403		101,529
Investment in unconsolidated affiliates		2,158				4,162				2,158		4,162		6,221
Capital expenditures										11,435		17,750		14,202
Total assets		553,480				527,200				553,480		527,200		506,625
Engine Management [Member] | Intersegment Eliminations [Member]
Financial information for reportable segment [Abstract]
Net sales	[2]									23,367		24,995	[3]	22,268	[3]
Temperature Control [Member] | Reportable Segments [Member]
Financial information for reportable segment [Abstract]
Net sales	[2]									278,456		279,127	[3]	283,740	[3]
Depreciation and amortization										4,704		4,373		4,287
Operating income (loss)										14,586		19,609		17,563
Investment in unconsolidated affiliates		30,311				27,022				30,311		27,022		13,703
Capital expenditures										7,245		5,151		3,652
Total assets		205,039				177,006				205,039		177,006		171,136
Temperature Control [Member] | Intersegment Eliminations [Member]
Financial information for reportable segment [Abstract]
Net sales	[2]									8,160		7,334	[3]	7,293	[3]
Other [Member]
Financial information for reportable segment [Abstract]
Net sales	[2]									10,108		7,603	[3]	9,203	[3]
Depreciation and amortization										1,542		1,562		1,162
Operating income (loss)										(18,162)		(19,491)		(20,303)
Investment in unconsolidated affiliates		0				0				0		0		0
Capital expenditures										1,461		1,541		3,067
Total assets		$ 84,613				$ 83,361				84,613		83,361		90,936
Other [Member] | Intersegment Eliminations [Member]
Financial information for reportable segment [Abstract]
Net sales	[2]									$ (31,527)		$ (32,329)	[3]	$ (29,561)	[3]

[1] Revenues are attributed to countries based upon the location of the customer.

[2] Segment net sales include intersegment sales in our Engine Management and Temperature Control segments.

[3] Net sales and intersegment sales for 2017 and 2016 have not been restated and are reported under accounting standards in effect in the period presented, as we adopted ASU 2014-09, Revenue from Contracts with Customers, on January 1, 2018 using the modified retrospective method.

[4] Revenues for 2017 and 2016 have not been restated and are reported under accounting standards in effect in the period presented, as we adopted ASU 2014-09, Revenue from Contracts with Customers, on January 1, 2018 using the modified retrospective method.