Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Net sales	$ 371,669	$ 375,315	$ 748,360	$ 741,975
Cost of sales	238,306	237,608	482,949	474,742
Selling and administrative expenses	76,406	73,828	157,804	146,721
Total operating costs and expenses	314,712	311,436	640,753	621,463
Operating income	56,957	63,879	107,607	120,512
Interest expense	5,399	4,133	10,512	8,025
Other expense (income), net	1,712	947	3,519	2,710
Income before income taxes	49,846	58,799	93,576	109,777
Income taxes	12,230	9,370	21,968	21,530
Net income	$ 37,616	$ 49,429	$ 71,608	$ 88,247
Per common share:
Basic (in dollars per share)	$ 0.73	$ 0.94	$ 1.39	$ 1.66
Diluted (in dollars per share)	$ 0.73	$ 0.93	$ 1.38	$ 1.65
Weighted average common shares outstanding:
Basic (in shares)	51,251,149	52,581,804	51,454,844	53,055,980
Diluted (in shares)	51,743,483	53,135,742	51,965,343	53,608,447