Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities
Net income	$ 113,009	$ 102,305
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	10,749	9,716
Amortization	1,075	922
Share-based compensation	6,854	6,090
Excess tax benefits from share-based compensation	(4,141)	(4,367)
Equity earnings in unconsolidated investments	(209)	(52)
Other	(727)	(194)
Changes in operating assets and liabilities, net of effects of acquisitions:
Receivables	(79,891)	(65,638)
Product inventories	19,262	34,709
Prepaid expenses and other assets	(1,212)	1,063
Accounts payable	(61,544)	(57,641)
Accrued expenses and other current liabilities	33,995	26,933
Net cash provided by operating activities	37,220	53,846
Investing activities
Acquisition of businesses, net of cash acquired	(9,381)	(1,244)
Purchase of property and equipment, net of sale proceeds	(14,687)	(14,407)
Other investments, net	133	76
Net cash used in investing activities	(23,935)	(15,575)
Financing activities
Proceeds from revolving line of credit	658,720	596,642
Payments on revolving line of credit	(542,018)	(567,092)
Proceeds from asset-backed financing	121,600	0
Payments on asset-backed financing	(93,600)	0
Proceeds from long-term debt and other long-term liabilities	1,621	0
Payments on long-term debt and other long-term liabilities	0	(10)
Payments of deferred financing costs	(7)	(754)
Excess tax benefits from share-based compensation	4,141	4,367
Proceeds from stock issued under share-based compensation plans	8,090	19,040
Payments of cash dividends	(28,075)	(25,120)
Purchases of treasury stock	(135,155)	(53,027)
Net cash used in financing activities	(4,683)	(25,954)
Effect of exchange rate changes on cash and cash equivalents	(2,153)	(558)
Change in cash and cash equivalents	6,449	11,759
Cash and cash equivalents at beginning of period	8,006	12,463
Cash and cash equivalents at end of period	$ 14,455	$ 24,222