Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net earnings	$ 257,748	$ 267,963
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation of property and equipment	47,937	39,295
Gain on sale of property and equipment	(130)	(498)
Bad debt expense	3,894	4,806
Deferred income taxes	2,345	2,527
Stock-based compensation	1,700	3,441
Excess tax benefits from stock-based compensation	(5,469)	(1,274)
Amortization of non-compete agreements	263	263
Changes in operating assets and liabilities:
Trade accounts receivable	(70,560)	(83,552)
Inventories	(68,144)	(12,615)
Other current assets	18,539	8,496
Accounts payable	32,725	29,563
Accrued expenses	(8,587)	8,395
Income taxes	36,345	(5,036)
Other	(553)	(620)
Net cash provided by operating activities	248,053	261,154
Cash flows from investing activities:
Purchases of property and equipment	(88,723)	(88,020)
Proceeds from sale of property and equipment	2,988	4,112
Other	(206)	(20)
Net cash used in investing activities	(85,941)	(83,928)
Cash flows from financing activities:
Borrowings under credit facility	435,000	790,000
Payments against credit facility	(370,000)	(550,000)
Proceeds from exercise of stock options	22,423	6,911
Excess tax benefits from stock-based compensation	5,469	1,274
Purchases of common stock	(59,440)	(250,425)
Payments of dividends	(173,188)	(164,736)
Net cash used in financing activities	(139,736)	(166,976)
Effect of exchange rate changes on cash and cash equivalents	4,063	(3,580)
Net increase in cash and cash equivalents	26,439	6,670
Cash and cash equivalents at beginning of period	129,019	114,496
Cash and cash equivalents at end of period	155,458	121,166
Supplemental disclosure of cash flow information:
Cash paid for interest	2,873	1,155
Net cash paid for income taxes	$ 110,934	$ 162,891