Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash Flows from Operating Activities:
Net income	$ 134,927	$ 123,756
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	38,490	35,388
Loss on disposal of property and equipment	194	481
Increase (decrease) in deferred compensation liability	176	(320)
Provision for uncollectible accounts	837	997
(Benefit of) provision for deferred income taxes	(1,861)	598
Share-based compensation expense	11,684	11,497
Tax benefit from share-based compensation arrangements	(10,182)	(14,009)
Changes in assets and liabilities:
Accounts receivable	255	(16,181)
Inventories	(18,078)	(9,732)
Other assets	539	3,056
Accounts payable	(4,893)	8,305
Accrued liabilities	(3,751)	16,664
Deferred revenue	5,151	3,018
Net cash provided by operating activities	153,488	163,518
Cash Flows from Investing Activities:
Purchases of property and equipment	(43,230)	(39,927)
Proceeds from disposition of pharmaceutical product lines	3,000	3,000
Proceeds from sale of property and equipment	45	223
Acquisitions of intangible asset	(900)
Acquisition of a business, net of cash acquired		(2,600)
Net cash used by investing activities	(41,085)	(39,304)
Cash Flows from Financing Activities:
(Payments) borrowings on revolving credit facilities, net	(11,000)	24,903
Payment of notes payable	(682)	(643)
Repurchases of common stock	(91,152)	(166,016)
Proceeds from exercises of stock options and employee stock purchase plans	17,156	26,080
Tax benefit from share-based compensation arrangements	10,182	14,009
Net cash used by financing activities	(75,496)	(101,667)
Net effect of changes in exchange rates on cash	639	2,037
Net increase in cash and cash equivalents	37,546	24,584
Cash and cash equivalents at beginning of period	183,895	156,915
Cash and cash equivalents at end of period	$ 221,441	$ 181,499