Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating activities
Net income	$ 102,305	$ 89,969
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	9,716	8,481
Amortization	922	962
Share-based compensation	6,090	6,236
Excess tax benefits from share-based compensation	(4,367)	(2,534)
Equity earnings in unconsolidated investments	(52)	(187)
Goodwill impairment	0	6,946
Other	(194)	278
Changes in operating assets and liabilities, net of effects of acquisitions:
Receivables	(65,638)	(63,015)
Product inventories	34,709	39,644
Prepaid expenses and other assets	1,063	2,607
Accounts payable	(57,641)	(15,500)
Accrued expenses and other current liabilities	26,933	50,643
Net cash provided by operating activities	53,846	124,530
Investing activities
Acquisition of businesses, net of cash acquired	(1,244)	(4,580)
Purchase of property and equipment, net of sale proceeds	(14,407)	(13,717)
Other investments, net	76	(249)
Net cash used in investing activities	(15,575)	(18,546)
Financing activities
Proceeds from revolving line of credit	596,642	482,669
Payments on revolving line of credit	(567,092)	(415,641)
Payments on long-term debt and other long-term liabilities	(10)	(100,017)
Payments of deferred financing costs	(754)	0
Excess tax benefits from share-based compensation	4,367	2,534
Proceeds from stock issued under share-based compensation plans	19,040	13,180
Payments of cash dividends	(25,120)	(21,669)
Purchases of treasury stock	(53,027)	(55,088)
Net cash used in financing activities	(25,954)	(94,032)
Effect of exchange rate changes on cash and cash equivalents	(558)	(621)
Change in cash and cash equivalents	11,759	11,331
Cash and cash equivalents at beginning of period	12,463	17,487
Cash and cash equivalents at end of period	$ 24,222	$ 28,818