Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Net sales	$ 1,651,070	$ 1,488,499	$ 4,237,841	$ 3,695,353
Cost of goods sold	1,402,836	1,230,148	3,533,257	3,027,809
Gross profit	248,234	258,351	704,584	667,544
Selling, general and administrative expenses	90,299	91,525	282,072	282,011
Rationalization charges	2,315	2,505	13,026	7,247
Other pension and postretirement income	(12,297)	(9,712)	(37,934)	(29,122)
Income before interest and income taxes	167,917	174,033	447,420	407,408
Interest and other debt expense before loss on early extinguishment of debt	27,039	27,725	79,868	77,051
Loss on early extinguishment of debt	0	0	883	1,481
Interest and other debt expense	27,039	27,725	80,751	78,532
Income before income taxes	140,878	146,308	366,669	328,876
Provision for income taxes	34,586	33,457	92,620	80,253
Net income	$ 106,292	$ 112,851	$ 274,049	$ 248,623
Earnings per share
Basic net income per share (usd per share)	$ 0.96	$ 1.02	$ 2.48	$ 2.24
Diluted net income per share (usd per share)	$ 0.96	$ 1.01	$ 2.47	$ 2.23
Weighted average number of shares
Basic (in shares)	110,465	110,921	110,372	110,895
Effect of dilutive securities (in shares)	732	691	739	565
Diluted (in shares)	111,197	111,612	111,111	111,460