CONDENSED CONSOLIDATED STATEMENTS OF INCOME (LOSS) (Unaudited) - USD ($) shares in Thousands, $ 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		$ 1,260,656	$ 1,354,523	$ 2,530,038	$ 2,706,819
Cost of goods sold		1,083,092	1,158,700	2,166,807	2,310,914
Gross profit		177,564	195,823	363,231	395,905
Operating expenses:
Warehousing, marketing and administrative expenses		161,695	157,625	334,717	325,303
Impairment of goodwill				198,828
Defined benefit plan settlement loss			11,744		11,744
Operating income (loss)		15,869	26,454	(170,314)	58,858
Interest expense, net		6,299	5,677	13,038	11,574
Income (loss) before income taxes		9,570	20,777	(183,352)	47,284
Income tax expense		4,474	7,844	146	17,821
Net income (loss)		$ 5,096	$ 12,933	$ (183,498)	$ 29,463
Net income (loss) per share - basic:		$ 0.14	$ 0.35	$ (5.01)	$ 0.81
Average number of common shares outstanding - basic		36,673	36,512	36,659	36,552
Net income (loss) per share - diluted:	[1]	$ 0.14	$ 0.35	$ (5.01)	$ 0.80
Average number of common shares outstanding - diluted		36,873	36,910	36,659	36,897
Dividends declared per share		$ 0.14	$ 0.14	$ 0.28	$ 0.28

[1] As a result of the net loss in the six months ended June 30, 2017, the effect of potentially dilutive securities would have been anti-dilutive and has been omitted from the calculation of diluted earnings per share.