Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net earnings	$ 349,407	$ 321,820
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation of property and equipment	47,212	39,153
Gain on sale of property and equipment	(568)	(266)
Bad debt expense	7,087	7,240
Deferred income taxes	519	4,817
Stock based compensation	4,050	3,450
Excess tax benefits from stock based compensation	(2,682)	(8,957)
Amortization of non-compete agreements	290	445
Changes in operating assets and liabilities:
Trade accounts receivable	(88,580)	(79,679)
Inventories	(40,602)	(29,676)
Other current assets	(23,386)	(10,301)
Accounts payable	27,112	11,103
Accrued expenses	26,292	11,217
Income taxes	12,044	14,835
Other	(2,922)	3,895
Net cash provided by operating activities	315,273	289,096
Cash flows from investing activities:
Purchase of property and equipment	(145,559)	(88,323)
Proceeds from sale of property and equipment	4,291	1,102
Net increase in marketable securities	(87)	(63)
Increase in other assets	(79)	(122)
Net cash used in investing activities	(141,434)	(87,406)
Cash flows from financing activities:
Borrowings under line of credit	100,000	0
Payments against line of credit	(100,000)	0
Proceeds from exercise of stock options	9,039	23,785
Excess tax benefits from stock based compensation	2,682	8,957
Purchase of common stock	(9,080)	0
Payment of dividends	(163,219)	(156,810)
Net cash used in financing activities	(160,578)	(124,068)
Effect of exchange rate changes on cash	(682)	305
Net increase in cash and cash equivalents	12,579	77,927
Cash and cash equivalents at beginning of period	79,611	117,676
Cash and cash equivalents at end of period	92,190	195,603
Supplemental disclosure of cash flow information:
Cash paid during each period for interest	61	0
Cash paid during each period for income taxes	$ 192,408	$ 184,166