CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) [Abstract]
Net sales	[1]	$ 312,729	$ 288,977	$ 595,107	$ 527,888
Cost of sales		222,063	201,901	420,331	367,816
Gross profit		90,666	87,076	174,776	160,072
Selling, general and administrative expenses		60,076	54,758	117,436	107,756
Restructuring and integration expenses		1,235	771	2,782	1,012
Other income, net		314	297	630	559
Operating income		29,669	31,844	55,188	51,863
Other non-operating income, net		740	265	1,563	598
Interest expense		722	394	1,190	705
Earnings from continuing operations before taxes		29,687	31,715	55,561	51,756
Provision for income taxes		11,426	11,853	20,933	19,238
Earnings from continuing operations		18,261	19,862	34,628	32,518
Loss from discontinued operations, net of income taxes		(497)	(618)	(1,130)	(1,070)
Net earnings		$ 17,764	$ 19,244	$ 33,498	$ 31,448
Net earnings per common share - Basic:
Earnings from continuing operations (in dollars per share)		$ 0.80	$ 0.87	$ 1.52	$ 1.43
Discontinued operations (in dollars per share)		(0.02)	(0.02)	(0.05)	(0.04)
Net earnings per common share - Basic (in dollars per share)		0.78	0.85	1.47	1.39
Net earnings per common share - Diluted:
Earnings from continuing operations (in dollars per share)		0.78	0.86	1.48	1.41
Discontinued operations (in dollars per share)		(0.02)	(0.02)	(0.04)	(0.04)
Net earnings per common share - Diluted (in dollars per share)		0.76	0.84	1.44	1.37
Dividend declared per share (in dollars per share)		$ 0.19	$ 0.17	$ 0.38	$ 0.34
Average number of common shares (in shares)		22,820,079	22,705,310	22,833,263	22,673,811
Average number of common shares and dilutive common shares (in shares)		23,329,082	23,018,730	23,332,480	22,988,502

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