Borrowings - Additional Information (Detail) (USD $)	3 Months Ended			3 Months Ended			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	May 31, 2008 License and maintenance agreement [Member]	Mar. 31, 2013 Convertible senior notes [Member]	Dec. 31, 2012 Convertible senior notes [Member]	Jun. 30, 2011 Convertible senior notes [Member]	Mar. 31, 2013 Installment Loan [Member]	Mar. 31, 2012 Installment Loan [Member]	May 31, 2008 Installment Loan [Member]
Debt Instrument [Line Items]
Aggregate principal amount issued	$ 120,000,000	$ 120,000,000				$ 120,000,000
Coupon rate of notes				1.50%
Convertible senior notes due	Jul. 01, 2018
Measurement period adjustment against product				98.00%
Number of business day in conversion condition				5 days
Number of consecutive trading day 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%
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
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
Percentage of interest rate estimated	8.00%
Initial fair value of the liability component	79,400,000
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
Fair value of the Notes				121,900,000	135,800,000
Carrying amount of equity component of the Notes	32,311,000	33,549,000		32,300,000
Unamortized offering costs				2,100,000
Offering costs allocated to equity component				1,400,000
Additional one-time fee in relation to the agreement			6,400,000
Interest rate							3.00%		4.00%
Scheduled principal repayments of loan							400,000
Aggregate balance of loans							$ 900,000	$ 1,000,000