Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net sales	$ 1,124,391	$ 1,491,118	$ 1,495,889
Cost of sales	721,238	944,154	963,524
Selling and administrative expenses	279,783	310,516	300,601
Total operating costs and expenses	1,001,021	1,254,670	1,264,125
Operating income	123,370	236,448	231,764
Interest expense	15,944	20,629	16,841
Other expense (income), net	5,931	8,975	7,428
Income before income taxes	101,495	206,844	207,495
Income taxes	38,120	48,494	41,309
Net income	$ 63,375	$ 158,350	$ 166,186
Per common share:
Basic (in dollars per share)	$ 1.25	$ 3.09	$ 3.18
Diluted (in dollars per share)	$ 1.24	$ 3.07	$ 3.15
Dividends
Basic (in shares)	50,880,846	51,213,518	52,304,190
Diluted (in shares)	51,097,586	51,633,169	52,831,606