Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating activities
Net Income	$ 307,565	$ 243,551
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation	20,979	20,648
Amortization	975	1,049
Share-based compensation	11,095	10,243
Equity earnings in unconsolidated investments, net	(248)	(210)
Impairment of goodwill and other assets	6,944	0
Other	1,092	5,334
Changes in operating assets and liabilities, net of effects of acquisitions:
Receivables	(135,129)	(98,538)
Product inventories	99,767	68,827
Prepaid expenses and other assets	311	1,231
Accounts payable	3,385	(29,782)
Accrued expenses and other current liabilities	72,178	20,900
Net Cash Provided by operating activities	388,914	243,253
Investing activities
Acquisition of businesses, net of cash acquired	(24,655)	(8,913)
Purchases of property and equipment, net of sale proceeds	(16,897)	(26,926)
Net cash used in investing activities	(41,552)	(35,839)
Financing activities
Proceeds from revolving line of credit	749,840	836,534
Payments on revolving line of credit	(909,637)	(1,011,430)
Proceeds from asset-backed financing	261,700	189,000
Payments on asset-backed financing	(266,700)	(136,300)
Payments on term facility	(6,938)	0
Proceeds from short-term borrowings and current portion of long-term debt	13,255	27,633
Payments on short-term borrowings and current portion of long-term debt	(13,291)	(24,962)
Payments of deferred and contingent acquisition consideration	(281)	(311)
Payments of deferred financing costs	(12)	0
Proceeds from stock issued under share-based compensation plans	16,696	17,042
Payments of cash dividends	(68,599)	(61,752)
Purchases of treasury stock	(76,194)	(23,188)
Net cash used in financing activities	(300,161)	(187,734)
Effect of exchange rate changes on cash and cash equivalents	(1,035)	655
Change in cash and cash equivalents	46,166	20,335
Cash and cash equivalents at beginning of period	28,583	16,358
Cash and cash equivalents at end of period	$ 74,749	$ 36,693