Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Net sales	$ 306,693	$ 314,941	$ 595,025	$ 615,515
Cost of sales	197,173	204,121	383,428	402,477
Selling and administrative expenses	62,060	60,171	122,610	118,494
Total operating costs and expenses	259,233	264,292	506,038	520,971
Operating income	47,460	50,649	88,987	94,544
Interest expense	2,815	2,586	5,806	5,306
Other (income) expense, net	(824)	237	(597)	318
Income before income taxes	45,469	47,826	83,778	88,920
Income taxes	12,257	13,599	21,718	25,617
Net income	$ 33,212	$ 34,227	$ 62,060	$ 63,303
Per common share:
Basic (in dollars per share)	$ 0.61	$ 0.62	$ 1.14	$ 1.15
Diluted (in dollars per share)	0.61	0.61	1.14	1.14
Dividends (in dollars per share)	$ 0.13	$ 0.12	$ 0.25	$ 0.24
Weighted average common shares outstanding:
Basic (in shares)	54,168,562	55,134,890	54,207,145	55,111,019
Diluted (in shares)	54,642,071	55,695,258	54,662,389	55,677,166