CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Ordinary Shares	Additional Paid-in Capital	Accumulated Other Comprehensive Income (loss)	Retained Earnings (Accumulated Deficit)	Comprehensive Income
Balance at Dec. 31, 2008	$ 214,080	$ 131	$ 225,180	$ 81	$ (11,312)
Balance (in shares) at Dec. 31, 2008		31,774,620
Increase (Decrease) in Stockholders' Equity
Net income	12,886				12,886	12,886
Unrealized losses on available-for-sale securities, net of taxes	(157)			(157)		(157)
Unrealized gains (losses) on derivative contracts, net of taxes	443			443		443
Comprehensive net income	13,172					13,172
Share-based compensation	10,736		10,736
Exercise of share options	2,227	3	2,223
Exercise of share options (in shares)		700,624
Issuance of shares pursuant to employee share purchase plan	1,437	1	1,437
Issuance of shares pursuant to employee share purchase plan (in shares)		206,529
Income tax benefit from share options exercised	1,231		1,231
Balance at Dec. 31, 2009	242,883	135	240,807	367	1,574
Balance (in shares) at Dec. 31, 2009		32,681,773
Increase (Decrease) in Stockholders' Equity
Net income	13,540				13,540	13,540
Unrealized losses on available-for-sale securities, net of taxes	(90)			(90)		(90)
Unrealized gains (losses) on derivative contracts, net of taxes	677			677		677
Comprehensive net income	14,127					14,127
Share-based compensation	14,101		14,101
Exercise of share options	6,892	6	6,886
Exercise of share options (in shares)		1,349,891
Issuance of shares pursuant to employee share purchase plan	2,586		2,586
Issuance of shares pursuant to employee share purchase plan (in shares)		199,540
Income tax benefit from share options exercised	1,101		1,101
Balance at Dec. 31, 2010	281,690	141	265,481	954	15,114
Balance (in shares) at Dec. 31, 2010		34,231,204
Increase (Decrease) in Stockholders' Equity
Net income	9,977				9,977	9,977
Unrealized losses on available-for-sale securities, net of taxes	(109)			(109)		(109)
Unrealized gains (losses) on derivative contracts, net of taxes	(2,009)			(2,009)		(2,009)
Comprehensive net income	7,859					7,859
Share-based compensation	21,412		21,412
Exercise of share awards	14,000	7	13,993
Exercise of share awards (in shares)		1,810,582
Issuance of shares pursuant to employee share purchase plan	4,455	1	4,454
Issuance of shares pursuant to employee share purchase plan (in shares)		243,256
Issuance of shares in connection with public offering	104,217	16	104,201
Issuance of shares in connection with public offering (in shares)		3,450,000
Share-based compensation related to acquisitions	6,303		6,303
Income tax benefit from share options exercised	2,411		2,411
Balance at Dec. 31, 2011	$ 442,347	$ 165	$ 418,255	$ (1,164)	$ 25,091
Balance (in shares) at Dec. 31, 2011		39,735,042