Stockholders' Equity-Common and Preferred Shares - Summary of Gain (Loss) from the Change in Fair Value of Warrants and Other Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Gain Loss From Change In Fair Value Of Warrants And Other Financial Instruments [Line Items]
Total gain (loss) on change in fair market value of derivatives		$ 6	$ 2,222
Committed Equity Financing Facility [Member]
Gain Loss From Change In Fair Value Of Warrants And Other Financial Instruments [Line Items]
Total gain (loss) on change in fair market value of derivatives			3
Direct Registration Series I Warrants [Member]
Gain Loss From Change In Fair Value Of Warrants And Other Financial Instruments [Line Items]
Total gain (loss) on change in fair market value of derivatives		6	102
Gain Recognized in Connection with Warrant Exchange Agreements [Member]
Gain Loss From Change In Fair Value Of Warrants And Other Financial Instruments [Line Items]
Total gain (loss) on change in fair market value of derivatives			690
Private Placement Warrants [Member]
Gain Loss From Change In Fair Value Of Warrants And Other Financial Instruments [Line Items]
Total gain (loss) on change in fair market value of derivatives			$ 1,427