Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Net income	$ 19,991	$ 36,446
Adjustments to reconcile net income to net cash provided by operating activities:
Non-cash share-based compensation expense	4,904	3,456
Non-cash interest expense	2,245	1,956
Non-cash charge for contingent consideration	1,112	471
Non-cash charge for option amortization	1,071
Deferred tax provision	(4,381)	(2,468)
Depreciation and amortization expense	9,561	9,421
Other, net	(2,477)	(2,815)
Changes in assets and liabilities:
Accounts receivable	15,353	(15,564)
Inventory	4,289	(10,764)
Prepaid expenses and other current assets	608	2,344
Prepaid income taxes and income taxes payable	(6,069)	12,447
Other assets	670	553
Accounts payable	4,840	5,947
Accrued expenses and other current liabilities	1,697	(2,278)
Other non-current liabilities	(103)	(93)
Net cash provided by operating activities	53,311	39,059
Cash flows from investing activities:
Purchase of property, equipment and building improvements	(267)	(1,827)
Purchase of short-term investments	(36,192)	(51,824)
Maturities of short-term investments	54,353	26,410
Net cash provided by (used in) investing activities	17,894	(27,241)
Cash flows from financing activities:
Payment for treasury shares acquired	(49,996)	(45,000)
Forward share purchase		(5,000)
Net proceeds from issuance of common stock	5,558	2,109
Excess tax benefits from share-based payment arrangements	4,827	271
Net cash used in financing activities	(39,611)	(47,620)
Effect of exchange rate changes on cash	699	458
Net increase (decrease) in cash and cash equivalents	32,293	(35,344)
Cash and cash equivalents at beginning of period	331,352	426,732
Cash and cash equivalents at end of period	$ 363,645	$ 391,388