Equity and Liability Components of Notes (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Principal amount of the Notes outstanding	$ 365,422	$ 387,042
Unamortized discount of liability component	(22,063)	(24,907)
Less: current portion	3,255	3,245
Long-term debt	340,104	358,890
Convertible Senior Notes
Debt Instrument [Line Items]
Principal amount of the Notes outstanding	150,000	150,000
Unamortized discount of liability component	(17,420)	(19,372)
Net carrying amount of liability component	132,580	130,628
Less: current portion	0	0
Long-term debt	132,580	130,628
Carrying value of equity component, net of issuance costs	$ 20,993	$ 20,993
Remaining amortization period of discount on the liability component	3 years 9 months 18 days	4 years 3 months 18 days