Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net earnings	$ 267,963	$ 242,445
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation of property and equipment	39,295	35,190
Gain on sale of property and equipment	(498)	(412)
Bad debt expense	4,806	5,421
Deferred income taxes	2,527	1,100
Stock-based compensation	3,441	3,000
Excess tax benefits from stock-based compensation	(1,274)	(1,488)
Amortization of non-compete agreements	263	263
Changes in operating assets and liabilities:
Trade accounts receivable	(83,552)	(93,420)
Inventories	(12,615)	(34,703)
Other current assets	8,496	(3,021)
Accounts payable	29,563	18,235
Accrued expenses	8,395	18,046
Income taxes	(5,036)	31,707
Other	(620)	566
Net cash provided by operating activities	261,154	222,929
Cash flows from investing activities:
Purchases of property and equipment	(88,020)	(97,560)
Proceeds from sale of property and equipment	4,112	2,720
Net increase in marketable securities	0	(2)
Net increase in other assets	(20)	(69)
Net cash used in investing activities	(83,928)	(94,911)
Cash flows from financing activities:
Borrowings under line of credit	790,000	380,000
Payments against line of credit	(550,000)	(310,000)
Proceeds from exercise of stock options	6,911	5,143
Excess tax benefits from stock-based compensation	1,274	1,488
Purchases of common stock	(250,425)	(8,847)
Payments of dividends	(164,736)	(148,353)
Net cash used in financing activities	(166,976)	(80,569)
Effect of exchange rate changes on cash and cash equivalents	(3,580)	(15)
Net increase in cash and cash equivalents	6,670	47,434
Cash and cash equivalents at beginning of period	114,496	58,506
Cash and cash equivalents at end of period	121,166	105,940
Supplemental disclosure of cash flow information:
Cash paid during each period for interest	1,155	320
Net cash paid during each period for income taxes	$ 162,891	$ 99,348