Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities
Net income	$ 146,031	$ 125,645
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	15,020	11,920
Amortization	1,288	771
Share-based compensation	7,373	7,112
Excess tax benefits from share-based compensation	(6,582)	(4,916)
Equity earnings in unconsolidated investments, net	(113)	(259)
Other	3,799	2,314
Changes in operating assets and liabilities, net of effects of acquisitions:
Receivables	(71,936)	(78,662)
Product inventories	23,624	52,463
Prepaid expenses and other assets	(1,094)	296
Accounts payable	(49,479)	(66,035)
Accrued expenses and other current liabilities	75,239	27,334
Net cash provided by operating activities	143,170	77,983
Investing activities
Acquisition of businesses, net of cash acquired	(19,314)	(602)
Purchase of property and equipment, net of sale proceeds	(30,388)	(21,299)
Payments to fund credit agreement	(3,852)	(6,300)
Collections from credit agreement	3,300	4,557
Other investments, net	21	75
Net cash used in investing activities	(50,233)	(23,569)
Financing activities
Proceeds from revolving line of credit	873,854	721,835
Payments on revolving line of credit	(866,801)	(690,677)
Proceeds from asset-backed financing	145,000	128,400
Payments on asset-backed financing	(90,000)	(85,800)
Proceeds from short-term borrowings, long-term debt and other long-term liabilities	15,705	4,948
Payments on short-term borrowings, long-term debt and other long term liabilities	(16,107)	(4,678)
Excess tax benefits from share-based compensation	6,582	4,916
Proceeds from stock issued under share-based compensation plans	10,978	10,906
Payments of cash dividends	(37,007)	(32,008)
Purchases of treasury stock	(117,901)	(90,306)
Net cash used in financing activities	(75,697)	(32,464)
Effect of exchange rate changes on cash and cash equivalents	(185)	(7,276)
Change in cash and cash equivalents	17,055	14,674
Cash and cash equivalents at beginning of period	13,237	14,830
Cash and cash equivalents at end of period	$ 30,292	$ 29,504