Borrowings - Loan Agreement - Additional Information (Detail) - USD ($) $ in Thousands				3 Months Ended	12 Months Ended
	Dec. 22, 2015	Feb. 25, 2015	Nov. 06, 2014	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Nov. 30, 2012
Schedule Of Debt Instruments [Line Items]
Extension period for interest-only payment			4 months
Repayment of notes				$ 40,000
Debt issuance costs						$ 100
Interest expense					$ 19,232	18,230	$ 10,938
Loan and Security Agreement [Member]
Schedule Of Debt Instruments [Line Items]
Discount on loan recorded as a non-current liability to be paid upon full repayment or maturity of the loans				1,200	1,200
2022 Notes [Member]
Schedule Of Debt Instruments [Line Items]
Aggregate principal amount of loan	$ 175,000
Debt issuance costs				5,840	5,840
Debt issuance costs	$ 900
Interest expense					500
2022 Notes [Member] | Modified Loan Agreement [Member]
Schedule Of Debt Instruments [Line Items]
Debt issuance costs				300	300
Hercules [Member]
Schedule Of Debt Instruments [Line Items]
Initial debt discount				1,600	1,600
Interest expense					5,400	$ 4,700	$ 4,900
Hercules [Member] | Loan and Security Agreement [Member]
Schedule Of Debt Instruments [Line Items]
Aggregate principal amount of loan		$ 40,000						$ 40,000
Outstanding principal balance repayment start date		Jun. 01, 2016
Outstanding principal balance repayment end date		Nov. 01, 2018
Extended maturity period on principal payment		6 months
Hercules [Member] | 2022 Notes [Member]
Schedule Of Debt Instruments [Line Items]
Aggregate principal amount of loan				$ 40,000	40,000
Hercules [Member] | 2022 Notes [Member] | Modified Loan Agreement [Member]
Schedule Of Debt Instruments [Line Items]
Debt issuance costs					$ 900