Fair Value Measurements - Summary of Financial Assets and Liabilities Subject to Fair Value Measurements on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability	$ 9,998	$ 12,237
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability	9,998	12,237
Fair Value, Measurements, Recurring [Member] \| Series C-1 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability		37
Fair Value, Measurements, Recurring [Member] \| Common Stock Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability	9,998	12,200
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member] \| Series C-1 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member] \| Common Stock Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Series C-1 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Common Stock Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability	9,998	12,237
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member] \| Series C-1 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability		37
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member] \| Common Stock Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liability	$ 9,998	$ 12,200

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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