Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities
Net income	$ 101,610	$ 86,242
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation	9,743	7,687
Amortization	735	532
Share-based compensation	4,850	4,850
Excess tax benefits from share-based compensation	(3,203)	(4,568)
Equity earnings in unconsolidated investments, net	(62)	(191)
Other	2,270	1,339
Changes in operating assets and liabilities, net of effects of acquisitions:
Receivables	(187,526)	(177,193)
Product inventories	(14,481)	(7,849)
Prepaid expenses and other assets	(1,729)	4
Accounts payable	15,041	487
Accrued expenses and other current liabilities	58,995	32,014
Net cash used in operating activities	(13,757)	(56,646)
Investing activities
Acquisition of businesses, net of cash acquired	(19,211)	(479)
Purchase of property and equipment, net of sale proceeds	(25,779)	(16,200)
Payments to fund credit agreement	(2,232)	(5,350)
Collections from credit agreement	2,475	3,407
Other investments, net	17	59
Net cash used in investing activities	(44,730)	(18,563)
Financing activities
Proceeds from revolving line of credit	629,351	526,116
Payments on revolving line of credit	(604,470)	(466,005)
Proceeds from asset-backed financing	145,000	128,400
Payments on asset-backed financing	(2,800)	(16,000)
Proceeds from short-term borrowings, long-term debt and other long-term liabilities	12,110	4,110
Payments on short-term borrowings, long-term debt and other long term liabilities	(6,987)	(2,209)
Excess tax benefits from share-based compensation	3,203	4,568
Proceeds from stock issued under share-based compensation plans	5,699	8,372
Payments of cash dividends	(23,957)	(20,855)
Purchases of treasury stock	(80,478)	(62,701)
Net cash provided by financing activities	76,671	103,796
Effect of exchange rate changes on cash and cash equivalents	(870)	(4,473)
Change in cash and cash equivalents	17,314	24,114
Cash and cash equivalents at beginning of period	13,237	14,830
Cash and cash equivalents at end of period	$ 30,551	$ 38,944