Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Net sales	$ 311,561	$ 291,434	$ 906,586	$ 906,949
Cost of sales	198,600	191,132	582,028	593,609
Selling and administrative expenses	61,144	56,555	183,754	175,049
Total operating costs and expenses	259,744	247,687	765,782	768,658
Operating income	51,817	43,747	140,804	138,291
Interest expense	3,020	2,637	8,826	7,944
Other expense (income), net	621	(545)	24	(228)
Income before income taxes	48,176	41,655	131,954	130,575
Income taxes	11,348	7,984	33,066	33,601
Net income	$ 36,828	$ 33,671	$ 98,888	$ 96,974
Per common share:
Basic (in dollars per share)	$ 0.68	$ 0.61	$ 1.82	$ 1.76
Diluted (in dollars per share)	0.67	0.61	1.81	1.74
Dividends (in dollars per share)	$ 0.13	$ 0.12	$ 0.38	$ 0.36
Weighted average common shares outstanding:
Basic (in shares)	54,206,064	55,199,315	54,206,798	55,140,774
Diluted (in shares)	54,572,315	55,588,092	54,643,739	55,647,971