Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating activities
Net income	$ 69,973	$ 68,594
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation	6,338	5,559
Amortization	622	638
Share-based compensation	4,111	4,306
Excess tax benefits from share-based compensation	(3,187)	(1,609)
Equity earnings in unconsolidated investments	(55)	(171)
Other	(1,633)	1,248
Changes in operating assets and liabilities, net of effects of acquisitions:
Receivables	(165,713)	(157,829)
Product inventories	(24,134)	(13,289)
Prepaid expenses and other assets	459	2,612
Accounts payable	39,458	88,946
Accrued expenses and other current liabilities	40,783	34,516
Net cash used in operating activities	(32,978)	33,521
Investing activities
Acquisition of businesses, net of cash acquired	(1,188)	(4,429)
Purchase of property and equipment, net of sale proceeds	(10,500)	(9,520)
Other investments, net	29	(166)
Net cash used in investing activities	(11,659)	(14,115)
Financing activities
Proceeds from revolving line of credit	399,472	345,631
Payments on revolving line of credit	(329,928)	(183,118)
Payments on long-term debt and other long-term liabilities	(10)	(100,012)
Excess tax benefits from share-based compensation	3,187	1,609
Proceeds from stock issued under share-based compensation plans	13,489	7,879
Payments of cash dividends	(16,308)	(14,223)
Purchases of treasury stock	(10,437)	(43,866)
Net cash provided by financing activities	59,465	13,900
Effect of exchange rate changes on cash and cash equivalents	(355)	(482)
Change in cash and cash equivalents	14,473	32,824
Cash and cash equivalents at beginning of period	12,463	17,487
Cash and cash equivalents at end of period	$ 26,936	$ 50,311