Borrowings (Details Textual) (USD $)	6 Months Ended		6 Months Ended			6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 License and maintenance agreement [Member]	Jun. 30, 2012 Convertible senior notes [Member] Rate	Jun. 30, 2011 Convertible senior notes [Member]	Jun. 30, 2012 Installment Bank Loan [Member] Installment	Oct. 31, 2011 Installment Bank Loan [Member]	May 31, 2008 Installment Bank Loan [Member]
Debt Instrument [Line Items]
Aggregate principal amount issued	$ 120,000,000	$ 120,000,000			$ 120,000,000		$ 1,000,000
Coupon rate of notes				1.50%
Measurement period adjustment against product				98.00%
Number of business days in conversion condition				5 days
Number of consecutive trading days in condition				10 days
Number of trading days in condition				20 or more trading days
Number of consecutive trading days in condition				30 days
Percentage of applicable conversion price				130.00%
Initial conversion rate for the Notes				23.8126
Principal amount of Notes				1,000
Conversion price of Notes				$ 41.99
Percentage of principal amount of the Notes being repurchased				100.00%
Conditions for redemption of notes				Company may redeem for cash all or part of the Notes (except for the Notes that the Company is required to repurchase as described above) if the last reported sale price of the common stock exceeds 140% of the applicable conversion price for 20 or more trading days in a period of 30 consecutive trading days ending on the trading day immediately prior to the date of the redemption notice.
Percentage of applicable conversion price under redemption				140.00%
Number of trading days under redemption				20 or more trading days
Number of consecutive trading days under redemption				30 days
Amount allocated to the embedded conversion option				40,600,000
Offering costs				4,300,000
Offering costs classified as debt issuance costs				2,900,000
Unamortized offering costs				2,400,000
Offering costs allocated to equity component				1,400,000
Unamortized debt discount	35,952,000	38,263,000		36,000,000
Period of amortization for unamortized debt discount				6 years
Additional one-time fee in relation to the agreement			6,400,000
Effective interest rate of bank loan								4.00%
Scheduled principal repayments of loan						400,000
Loan inception payment						400,000
Liability for the loan	120,923,000							400,000
Number of installment loans						5
Interest rate							3.00%
Borrowings (Textual) [Abstract]
Convertible senior notes due	Jul. 01, 2018
Conditions for conversion of notes	(a) during the five business-day period after any ten consecutive trading-day period (the “measurement period”) in which the trading price per Note for each day of that measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the applicable conversion rate on each such day; (b) during any calendar quarter (and only during such quarter) after the calendar quarter ended September 30, 2011, if the last reported sale price of the common stock for 20 or more trading days in a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter exceeds 130% of the applicable conversion price in effect on the last trading day of the immediately preceding calendar quarter; (c) upon the occurrence of specified corporate events; or (d) if the Company calls the Notes for redemption
Percentage of interest rate estimated	8.00%
Initial fair value of the liability component	$ 79,400,000
Number of shares distributed	0