Industry Segment and Geographic Data (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) Customer Segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of reportable operating segments | Segment									2
Financial information for reportable segment [Abstract]
Net sales	$ 229,799	$ 300,795	$ 288,977	$ 238,911	$ 204,967	$ 270,037	$ 269,382	$ 227,589	$ 1,058,482	$ 971,975	$ 980,392
Depreciation and amortization									20,457	17,637	17,295
Operating income (loss)									98,067	75,860	85,338
Investment in equity affiliates	19,924				20,622				19,924	20,622	20,004
Capital expenditures									20,921	18,047	13,904
Total assets	768,697				681,064				768,697	681,064	673,551
Reconciliation of segment operating income to net earnings [Abstract]
Operating income									98,067	75,860	85,338
Other non-operating income (expense)									2,059	(220)	(1,969)
Interest expense									1,556	1,537	1,616
Earnings from continuing operations before taxes									98,570	74,103	81,753
Income tax expense									36,158	25,983	28,854
Earnings from continuing operations	8,839	21,055	19,862	12,656	5,779	19,194	13,808	9,339	62,412	48,120	52,899
Discontinued operations, net of tax	(487)	(425)	(618)	(452)	(553)	(728)	(430)	(391)	(1,982)	(2,102)	(9,870)
Net earnings	8,352	20,630	19,244	12,204	5,226	18,466	13,378	8,948	60,430	46,018	43,029
Revenues [Abstract]
Revenues	229,799	$ 300,795	$ 288,977	$ 238,911	204,967	$ 270,037	$ 269,382	$ 227,589	1,058,482	971,975	980,392
Long-lived assets [Abstract]
Long-lived assets	243,349				190,586				$ 243,349	$ 190,586	$ 192,578
Number of largest individual customers | Customer									5
Net sales by major customer									70.00%	68.00%	69.00%
Litigation charge									$ 0	$ 0	$ 10,650
Five Largest Individual Customers [Member]
Long-lived assets [Abstract]
Net sales by major customer									70.00%	68.00%	69.00%
O' Reilly Automotive, Inc. [Member]
Long-lived assets [Abstract]
Net sales by major customer									20.00%
NAPA Auto Parts [Member]
Long-lived assets [Abstract]
Net sales by major customer									18.00%
Advance Auto Parts, Inc. [Member]
Long-lived assets [Abstract]
Net sales by major customer									17.00%
AutoZone, Inc [Member]
Long-lived assets [Abstract]
Net sales by major customer									11.00%
United States [Member]
Financial information for reportable segment [Abstract]
Net sales									$ 952,019	$ 881,206	$ 884,701
Revenues [Abstract]
Revenues									952,019	881,206	884,701
Long-lived assets [Abstract]
Long-lived assets	204,592				155,438				204,592	155,438	158,350
Canada [Member]
Financial information for reportable segment [Abstract]
Net sales									53,324	48,072	51,526
Revenues [Abstract]
Revenues									53,324	48,072	51,526
Long-lived assets [Abstract]
Long-lived assets	1,344				1,190				1,344	1,190	1,546
Europe [Member]
Financial information for reportable segment [Abstract]
Net sales									14,703	16,305	18,061
Revenues [Abstract]
Revenues									14,703	16,305	18,061
Long-lived assets [Abstract]
Long-lived assets	13,612				12,324				13,612	12,324	11,725
Other Foreign [Member]
Financial information for reportable segment [Abstract]
Net sales									38,436	26,392	26,104
Revenues [Abstract]
Revenues									38,436	26,392	26,104
Long-lived assets [Abstract]
Long-lived assets	23,801				21,634				23,801	21,634	20,957
Intersegment Eliminations [Member]
Financial information for reportable segment [Abstract]
Net sales									0	0	0
Revenues [Abstract]
Revenues									0	0	0
Engine Management [Member] | Reportable Segments [Member]
Financial information for reportable segment [Abstract]
Net sales									765,539	698,021	709,263
Depreciation and amortization									15,008	12,256	12,425
Operating income (loss)									101,529	88,007	103,861
Investment in equity affiliates	6,221				6,430				6,221	6,430	6,368
Capital expenditures									14,202	13,038	10,748
Total assets	506,625				413,102				506,625	413,102	409,275
Reconciliation of segment operating income to net earnings [Abstract]
Operating income									101,529	88,007	103,861
Revenues [Abstract]
Revenues									765,539	698,021	709,263
Engine Management [Member] | Intersegment Eliminations [Member]
Financial information for reportable segment [Abstract]
Net sales									22,268	20,178	23,633
Revenues [Abstract]
Revenues									22,268	20,178	23,633
Temperature Control [Member] | Reportable Segments [Member]
Financial information for reportable segment [Abstract]
Net sales									283,740	264,478	259,065
Depreciation and amortization									4,287	4,329	4,171
Operating income (loss)									17,563	6,382	6,445
Investment in equity affiliates	13,703				14,192				13,703	14,192	13,636
Capital expenditures									3,652	3,027	2,624
Total assets	171,136				177,201				171,136	177,201	173,070
Reconciliation of segment operating income to net earnings [Abstract]
Operating income									17,563	6,382	6,445
Revenues [Abstract]
Revenues									283,740	264,478	259,065
Temperature Control [Member] | Intersegment Eliminations [Member]
Financial information for reportable segment [Abstract]
Net sales									7,293	6,542	6,966
Revenues [Abstract]
Revenues									7,293	6,542	6,966
Other [Member]
Financial information for reportable segment [Abstract]
Net sales									9,203	9,476	12,064
Depreciation and amortization									1,162	1,052	699
Operating income (loss)									(21,025)	(18,529)	(24,968)
Investment in equity affiliates	0				0				0	0	0
Capital expenditures									3,067	1,982	532
Total assets	$ 90,936				$ 90,761				90,936	90,761	91,206
Reconciliation of segment operating income to net earnings [Abstract]
Operating income									(21,025)	(18,529)	(24,968)
Revenues [Abstract]
Revenues									9,203	9,476	12,064
Other [Member] | Intersegment Eliminations [Member]
Financial information for reportable segment [Abstract]
Net sales									(29,561)	(26,720)	(30,599)
Revenues [Abstract]
Revenues									$ (29,561)	$ (26,720)	$ (30,599)