Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net earnings	$ 126,227	$ 127,606
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation of property and equipment	23,286	19,412
Loss (gain) on sale of property and equipment	106	(108)
Bad debt expense	2,070	2,883
Deferred income taxes	1,785	416
Stock-based compensation	1,000	1,620
Excess tax benefits from stock-based compensation	(5,092)	(451)
Amortization of non-compete agreements	132	132
Changes in operating assets and liabilities:
Trade accounts receivable	(64,372)	(66,065)
Inventories	(47,112)	(5,151)
Other current assets	13,472	18,140
Accounts payable	32,523	28,325
Accrued expenses	(5,792)	(5,059)
Income taxes	83,866	59,195
Other	(737)	(790)
Net cash provided by operating activities	161,362	180,105
Cash flows from investing activities:
Purchases of property and equipment	(29,681)	(43,922)
Proceeds from sale of property and equipment	949	1,663
Other	(200)	(23)
Net cash used in investing activities	(28,932)	(42,282)
Cash flows from financing activities:
Borrowings under credit facility	180,000	175,000
Payments against credit facility	(175,000)	(140,000)
Proceeds from exercise of stock options	20,514	2,080
Excess tax benefits from stock-based compensation	5,092	451
Purchases of common stock	(59,440)	(81,865)
Payments of dividends	(86,522)	(82,846)
Net cash used in financing activities	(115,356)	(127,180)
Effect of exchange rate changes on cash and cash equivalents	4,459	(4,349)
Net increase in cash and cash equivalents	21,533	6,294
Cash and cash equivalents at beginning of period	129,019	114,496
Cash and cash equivalents at end of period	150,552	120,790
Supplemental disclosure of cash flow information:
Cash paid for interest	1,389	358
Net cash (received) paid for income taxes	$ (12,197)	$ 16,292