CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Net sales	$ 1,926,722	$ 1,848,788	$ 3,922,408	$ 3,727,616
Cost of sales	1,459,342	1,355,535	2,992,903	2,730,295
Gross profit	467,380	493,253	929,505	997,321
Operating costs and expenses:
Selling and distribution	338,144	331,150	683,340	664,037
General and administrative	73,100	86,614	172,636	171,765
Amortization of intangibles	5,155	4,120	10,310	10,445
Facility closing and reorganization costs, net	5,817	(1,400)	15,103	(234)
Total operating costs and expenses	422,216	420,484	881,389	846,013
Operating income	45,164	72,769	48,116	151,308
Other (income) expense:
Interest expense	16,419	16,830	33,883	33,706
Other income, net	(805)	(2,210)	(1,761)	(3,207)
Total other expense	15,614	14,620	32,122	30,499
Income before income taxes	29,550	58,149	15,994	120,809
Income tax expense	11,903	24,778	8,106	48,237
Net income	$ 17,647	$ 33,371	$ 7,888	$ 72,572
Average common shares:
Basic (in shares)	90,882,415	91,244,745	90,796,585	91,406,969
Diluted (in shares)	91,369,030	91,679,813	91,365,946	91,995,078
Basic income per common share:
Net income (in dollars per share)	$ 0.19	$ 0.37	$ 0.09	$ 0.79
Diluted income per common share:
Net income (in dollars per share)	0.19	0.36	0.09	0.79
Cash dividends declared per common share (in dollars per share)	$ 0.09	$ 0.09	$ 0.18	$ 0.18