Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Disclosures [Abstract]

Estimated fair values of the liabilities measured on a recurring basis

At December 31, 2011, the estimated fair values of the liabilities measured on a recurring basis are as follows (in thousands):

	Fair Value Measurements at December 31, 2011
	Balance at December 31, 2011		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Embedded derivative liabilities	$	3,680	$	—	$	—	$	3,680
Warrant derivative liabilities	11,590		—		—		11,590
Total	$	15,270	$	—	$	—	$	15,270

Liabilities measured at estimated fair value using unobservable inputs

The following table presents the activity for liabilities measured at estimated fair value using unobservable inputs for the years ended December 31, 2012 and 2011 (in thousands):

	Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Embedded Derivative Liabilities			Warrant Derivative Liabilities			Total
Balance at December 31, 2010	$	5,170		$	932		$	6,102
Adjustments to estimated fair value	(1,150		)	10,658			9,508
Decrease of the embedded derivative liabilities for preferred shares converted into common stock	(361		)	—			(361		)
Reversal of previously accrued dividends	(72		)	—			(72		)
Dividends paid in Series C-1 Preferred Stock	41			—			41
Accrued dividends payable in Series C-1 Preferred Stock	52			—			52
Balance at December 31, 2011	3,680			11,590			15,270
Adjustments to estimated fair value	834			(3,832		)	(2,998		)
Reversal of previously accrued dividends	146			—			146
Transfer due to the removal of the derivative features	(4,660		)	(7,758		)	(12,418		)
Balance at December 31, 2012	$	—		$	—		$	—