Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash Flows from Operating Activities:
Net income	$ 44,867	$ 40,734
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	13,513	12,705
Loss on disposal of property and equipment	27	83
Increase in deferred compensation liability	114	176
Provision for uncollectible accounts	644	412
Provision for deferred income taxes	1,169	462
Share-based compensation expense	3,949	3,809
Tax benefit from share-based compensation arrangements	(5,310)	(4,518)
Changes in assets and liabilities:
Accounts receivable	(23,722)	(17,818)
Inventories	(8,472)	(8,687)
Other assets	6,301	(3,165)
Accounts payable	3,654	3,990
Accrued liabilities	(16,919)	(14,698)
Deferred revenue	869	1,699
Net cash provided by operating activities	20,684	15,184
Cash Flows from Investing Activities:
Purchases of property and equipment	(19,761)	(9,446)
Proceeds from disposition of pharmaceutical product lines	3,500	3,000
Proceeds from sale of property and equipment		2
Acquisitions of intangible assets	(659)	(900)
Net cash used by investing activities	(16,920)	(7,344)
Cash Flows from Financing Activities:
Borrowings on revolving credit facilities, net	48,000	11,000
Payment of notes payable	(238)	(224)
Repurchases of common stock	(63,778)	(27,630)
Proceeds from exercises of stock options and employee stock purchase plans	12,958	5,772
Tax benefit from share-based compensation arrangements	5,310	4,518
Net cash provided (used) by financing activities	2,252	(6,564)
Net effect of changes in exchange rates on cash	(1,638)	320
Net increase in cash and cash equivalents	4,378	1,596
Cash and cash equivalents at beginning of period	223,986	183,895
Cash and cash equivalents at end of period	$ 228,364	$ 185,491