Change in Fair Value of Derivative Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivatives, Fair Value [Line Items]
Beginning Balance			$ 17,994	$ 69,431
Record initial fair value of derivative liability on senior notes	3,500		3,500
(Gain) loss on change in fair value of derivative liability	(3,011)	(18,841)	(7,404)	(22,461)
Ending Balance	13,913	45,515	13,913	45,515
Warrant
Derivatives, Fair Value [Line Items]
Compensation income for change in fair value of warrants issued to former employees			(177)	(1,455)
Warrants Issued October 2009
Derivatives, Fair Value [Line Items]
Beginning Balance			6,894	54,854
(Gain) loss on change in fair value of derivative liability			(2,204)	(17,371)
Ending Balance	4,513	36,028	4,513	36,028
Warrants Issued October 2009 \| Warrant
Derivatives, Fair Value [Line Items]
Compensation income for change in fair value of warrants issued to former employees			(177)	(1,455)
Embedded Derivative Financial Instruments
Derivatives, Fair Value [Line Items]
Beginning Balance			11,100	14,577
Record initial fair value of derivative liability on senior notes	3,500		3,500
(Gain) loss on change in fair value of derivative liability			(5,200)	(5,977)
Ending Balance	9,400	8,600	9,400	8,600
Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
(Gain) loss on change in fair value of derivative liability				887
Ending Balance		$ 887		$ 887

Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

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-Name Accounting Standards Codification

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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. Includes assets not subject to a master netting arrangement and not elected to be offset.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

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