Borrowings - Schedule of Future Minimum Payments under the Loans Payable (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Less current portion	$ (1,058)	$ (13,346)
Loans payable, net of current portion	123,117	$ 106,806
4.50% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Remainder of 2015	2,813
2016	5,625
2017	5,625
2018	5,625
2019 and thereafter	136,250
Loans payable, gross	155,938
Less interest	(30,938)
Less unamortized discount	(40,396)
Loans payable, net of current portion	84,604
Loans Payable [Member] | Loan and Security Agreement [Member]
Debt Instrument [Line Items]
Remainder of 2015	2,157
2016	13,575
2017	18,167
2018	16,639
Loans payable, gross	50,538
Less interest	(9,337)
Less unamortized discount	(1,630)
Less current portion	(1,058)
Loans payable, net of current portion	$ 38,513