CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) [Abstract]
Net sales	[1]	$ 305,172	$ 286,636	$ 588,938	$ 548,462
Cost of sales		216,267	205,347	422,070	394,584
Gross profit		88,905	81,289	166,868	153,878
Selling, general and administrative expenses		60,536	57,750	120,536	115,467
Restructuring and integration expenses		644	231	644	3,067
Other income (expense), net		3	42	(3)	313
Operating income		27,728	23,350	45,685	35,657
Other non-operating income, net		1,411	480	2,057	449
Interest expense		1,722	1,251	2,811	1,883
Earnings from continuing operations before taxes		27,417	22,579	44,931	34,223
Provision for income taxes		6,862	5,752	11,272	8,799
Earnings from continuing operations		20,555	16,827	33,659	25,424
Loss from discontinued operations, net of income taxes		(1,123)	(882)	(2,011)	(1,490)
Net earnings		$ 19,432	$ 15,945	$ 31,648	$ 23,934
Net earnings per common share - Basic:
Earnings from continuing operations (in dollars per share)		$ 0.92	$ 0.75	$ 1.50	$ 1.13
Discontinued operations (in dollars per share)		(0.05)	(0.04)	(0.09)	(0.07)
Net earnings per common share - Basic (in dollars per share)		0.87	0.71	1.41	1.06
Net earnings per common share - Diluted:
Earnings from continuing operations (in dollars per share)		0.90	0.73	1.47	1.11
Discontinued operations (in dollars per share)		(0.05)	(0.04)	(0.09)	(0.07)
Net earnings per common share - Diluted (in dollars per share)		0.85	0.69	1.38	1.04
Dividends declared per share (in dollars per share)		$ 0.23	$ 0.21	$ 0.46	$ 0.42
Average number of common shares (in shares)		22,328,292	22,471,428	22,374,785	22,484,894
Average number of common shares and dilutive common shares (in shares)		22,795,677	22,958,469	22,857,435	22,962,049

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