Consolidated Statements of Income $ in Thousands		12 Months Ended
		Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares
Income Statement [Abstract]
Net sales		$ 4,089,854	$ 3,612,914	$ 3,763,971
Cost of goods sold		3,428,738	3,079,378	3,209,845
Gross profit		661,116	533,536	554,126
Selling, general and administrative expenses		298,300	214,745	219,907
Rationalization charges		5,826	19,061	14,407
Income from operations		356,990	299,730	319,812
Interest and other debt expense before loss on early extinguishment of debt		110,257	67,813	66,926
Loss on early extinguishment of debt		7,052	0	0
Interest and other debt expense		117,309	67,813	66,926
Income before income taxes		239,681	231,917	252,886
(Benefit) provision for income taxes		(29,978)	78,566	80,473
Net income		$ 269,659	$ 153,351	$ 172,413
Basic net income per share (in dollars per share) | $ / shares	[1]	$ 2.44	$ 1.28	$ 1.41
Diluted net income per share (in dollars per share) | $ / shares	[1]	2.42	1.27	1.41
Dividends per share (in dollars per share) | $ / shares	[1]	$ 0.36	$ 0.34	$ 0.32
Stock split ratio (in shares)		2,000	2	2

[1] Per share amounts for 2016 and 2015 have been retroactively adjusted for the two-for-one stock split discussed in Note 1.