CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 129,014	$ 201,858	$ 160,377
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization, and accretion	33,367	28,977	12,283
Change in fair value of contingent consideration	8,659
Provision for (recovery of) doubtful accounts, net	2,128	(704)	(786)
Deferred tax provision	(5,657)	(67)	(1,712)
Stock compensation	14,661	14,803	12,782
Other	1,229	2,735	(391)
Changes in operating assets and liabilities, net of assets and liabilities acquired in the acquisition of businesses:
Trade accounts receivable	491	(63,199)	(39,449)
Inventories	(46,903)	(120,730)	(38,642)
Prepaid expenses and other current assets	23,511	(75,525)	(6,766)
Other assets	(3,028)	(5,385)	(1,651)
Trade accounts payable	18,932	38,237	19,742
Contingent consideration	(959)
Accrued expenses	(9,983)	850	16,468
Income taxes payable	(5,820)	5,722	5,480
Long-term liabilities	4,264	2,519	2,187
Net cash provided by operating activities	163,906	30,091	139,922
Cash flows from investing activities:
Proceeds from sales of short-term investments			26,080
Purchases of property and equipment	(61,575)	(55,538)	(22,489)
Acquisitions of businesses and equity method investment	(8,829)	(125,203)	(5,191)
Purchases of intangible assets	(4,958)	(4,025)
Net cash used in investing activities	(75,362)	(184,766)	(1,600)
Cash flows from financing activities:
Proceeds from issuance of short-term borrowings	307,000	45,000
Repayments of short-term borrowings	(274,000)	(45,000)
Cash paid for shares withheld for taxes	(6,535)	(22,634)	(2,584)
Excess tax benefit from stock compensation	2,457	15,330	3,525
Cash received from issuances of common stock		62	89
Loan origination costs on short-term borrowings	(1,807)
Contingent consideration paid	(29,041)
Cash paid for noncontrolling interest	(20,000)
Cash paid for repurchases of common stock	(220,695)	(19,918)	(10,082)
Net cash used in financing activities	(242,621)	(27,160)	(9,052)
Effect of exchange rates on cash	718	215	94
Net change in cash and cash equivalents	(153,359)	(181,620)	129,364
Cash and cash equivalents at beginning of year	263,606	445,226	315,862
Cash and cash equivalents at end of year	110,247	263,606	445,226
Cash paid during the year for:
Income taxes	66,899	62,405	82,493
Interest	3,338	88	59
Non-cash investing and financing activity:
Deferred purchase payments for acquisition of business	3,671
Accruals for purchases of property and equipment	489	3,268	247
Contingent consideration arrangement for acquisition of business	1,128	88,100
Accruals for asset retirement obligations	526	236	388
Accruals for shares withheld for taxes	1,804	2,460	1,598
Write-off for shares exercised with a tax deficit	$ 2,838