Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net sales	$ 372,587	$ 369,797	$ 1,120,947	$ 1,111,772
Cost of sales	234,421	236,880	717,370	711,622
Selling and administrative expenses	70,581	73,854	228,385	220,575
Total operating costs and expenses	305,002	310,734	945,755	932,197
Operating income	67,585	59,063	175,192	179,575
Interest expense	5,344	4,054	15,856	12,078
Other expense (income), net	2,524	2,447	6,043	5,157
Income before income taxes	59,717	52,562	153,293	162,340
Income taxes	13,948	13,453	35,916	34,983
Net income	$ 45,769	$ 39,109	$ 117,377	$ 127,357
Per common share:
Basic (in dollars per share)	$ 0.90	$ 0.76	$ 2.29	$ 2.42
Diluted (in dollars per share)	$ 0.89	$ 0.75	$ 2.27	$ 2.40
Weighted average common shares outstanding:
Basic (in shares)	50,926,521	51,569,764	51,276,801	52,555,130
Diluted (in shares)	51,230,845	52,080,676	51,718,574	53,091,468