Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net sales	$ 1,488,499	$ 1,321,342	$ 3,695,353	$ 3,441,635
Cost of goods sold	1,230,148	1,113,727	3,027,809	2,884,510
Gross profit	258,351	207,615	667,544	557,125
Selling, general and administrative expenses	91,525	76,065	282,011	233,816
Rationalization charges	2,505	3,195	7,247	48,594
Other pension and postretirement income	(9,712)	(4,340)	(29,122)	(13,320)
Income before interest and income taxes	174,033	132,695	407,408	288,035
Interest and other debt expense before loss on early extinguishment of debt	27,725	26,767	77,051	82,272
Loss on early extinguishment of debt	0	1,676	1,481	1,676
Interest and other debt expense	27,725	28,443	78,532	83,948
Income before income taxes	146,308	104,252	328,876	204,087
Provision for income taxes	33,457	22,978	80,253	45,117
Net income	$ 112,851	$ 81,274	$ 248,623	$ 158,970
Earnings per share
Basic net income per share (usd per share)	$ 1.02	$ 0.73	$ 2.24	$ 1.43
Diluted net income per share (usd per share)	$ 1.01	$ 0.73	$ 2.23	$ 1.43
Weighted average number of shares
Basic (in shares)	110,921	111,058	110,895	110,985
Effect of dilutive securities (in shares)	691	463	565	554
Diluted (in shares)	111,612	111,521	111,460	111,539