Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net earnings	$ 212,500	$ 173,659
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation of property and equipment	25,712	21,363
(Gain) loss on sale of property and equipment	(108)	284
Bad debt expense	4,791	4,258
Deferred income taxes	4,154	204
Stock based compensation	2,100	1,800
Excess tax benefits from stock based compensation	(8,103)	0
Amortization of non-compete agreements	297	297
Changes in operating assets and liabilities:
Trade accounts receivable	(66,190)	(91,320)
Inventories	(16,537)	(51,288)
Other current assets	1,242	(2,359)
Accounts payable	7,464	22,646
Accrued expenses	7,317	4,016
Income taxes	16,023	15,547
Other	(231)	2,170
Net cash provided by operating activities	190,431	101,277
Cash flows from investing activities:
Purchase of property and equipment	(50,980)	(56,324)
Proceeds from sale of property and equipment	1,325	1,635
Net (increase) decrease in marketable securities	(1)	4,976
(Increase) decrease in other assets	(87)	122
Net cash used in investing activities	(49,743)	(49,591)
Cash flows from financing activities:
Proceeds from exercise of stock options	20,201	5,353
Excess tax benefits from stock based compensation	8,103	0
Payment of dividends	(100,529)	(112,047)
Net cash used in financing activities	(72,225)	(106,694)
Effect of exchange rate changes on cash	(223)	724
Net increase (decrease) in cash and cash equivalents	68,240	(54,284)
Cash and cash equivalents at beginning of period	117,676	143,693
Cash and cash equivalents at end of period	185,916	89,409
Supplemental disclosure of cash flow information:
Cash paid during each period for income taxes	$ 113,810	$ 89,583