Borrowings - Schedule of Future Minimum Payments under the Loans Payable (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Loans payable, net of current portion	$ 103,427	$ 37,482
4.50% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
2014	5,594
2015	5,625
2016	5,625
2017	5,625
2018 and thereafter	141,875
Loans payable, gross	164,344
Less interest	(39,344)
Less unamortized discount	(52,422)
Loans payable, net of current portion	72,578
Loans Payable [Member] | Loan and Security Agreement [Member]
Debt Instrument [Line Items]
2014	12,353
2015	18,130
2016	17,916
Loans payable, gross	48,399
Less interest	(7,199)
Less unamortized discount	(2,103)
Less current portion	(8,248)
Loans payable, net of current portion	$ 30,849