Input to Lattice Model that was Used to Value Embedded Derivative (Detail) (2022 Notes, Embedded Derivative Financial Instruments, USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
2022 Notes | Embedded Derivative Financial Instruments
Derivative [Line Items]
Stock price	$ 0.34	$ 1.43
Conversion Rate	175.6697	175.6697
Conversion Price	$ 5.69	$ 5.69
Maturity date	Jul. 01, 2022	Jul. 01, 2022
Risk-free interest rate	2.30%	2.80%
Estimated stock volatility	85.00%	65.00%
Estimated credit spread	20.00%	33.00%