Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value of Financial Instruments [Abstract]

Estimated fair values of the liabilities measured on a recurring basis

	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

	Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Embedded Derivative			Warrant Derivative
	Liabilities			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	$	—		$	—		$	—