CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net sales	$ 1,274,494	$ 1,275,710	$ 2,524,979	$ 2,547,357
Cost of goods sold	1,072,558	1,087,451	2,134,518	2,178,169
Gross profit	201,936	188,259	390,461	369,188
Operating expenses:
Warehousing, marketing and administrative expenses	143,009	137,935	306,293	287,272
Operating income	58,927	50,324	84,168	81,916
Interest expense, net	2,856	7,070	5,969	14,236
Income before income taxes	56,071	43,254	78,199	67,680
Income tax expense	21,401	16,225	29,655	25,539
Net income	$ 34,670	$ 27,029	$ 48,544	$ 42,141
Net income per share-basic:
Net income per share-basic	$ 0.87	$ 0.67	$ 1.22	$ 1.03
Average number of common shares outstanding-basic	39,762	40,223	39,867	40,899
Net income per share-diluted:
Net income per share-diluted	$ 0.86	$ 0.66	$ 1.20	$ 1.01
Average number of common shares outstanding-diluted	40,328	40,887	40,475	41,626
Dividends declared per share	$ 0.14	$ 0.13	$ 0.28	$ 0.26