Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2012

Fair Value of Financial Instruments [Abstract]

Estimated fair values of the liabilities measured on a recurring basis

	Fair Value Measurements at June 30, 2012
	Balance at June 30, 2012		Quoted Prices in Active Markets (Level 1)		Significant Other Observable  Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Embedded derivative liabilities	$	4,062	$	—	$	—	$	4,062
Warrant derivative liabilities		9,744		—		—		9,744
Total	$	13,806	$	—	$	—	$	13,806
	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 Liabilities			Warrant  Derivative Liabilities			Total
Beginning balance at December 31, 2011	$	3,680		$	11,590		$	15,270
Adjustments to estimated fair value		(539	)		(5,415	)		(5,954	)
Accrued dividends payable in Series C-1 2 Preferred		101			—			101
Ending balance at March 31, 2012	$	3,242		$	6,175		$	9,417
Adjustments to estimated fair value		916			3,569			4,485
Accrued dividends payable in Series C-1 2 Preferred		(96	)		—			(96	)
Ending balance at June 30, 2012	$	4,062		$	9,744		$	13,806

	Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
	Embedded Derivative Liabilities			Warrant  Derivative Liabilities			Total
Beginning balance at December 31, 2010	$	5,170		$	932		$	6,102
Adjustments to estimated fair value		159			5,870			6,029
Forfeited accrued dividends payable in Series C-1 2 Preferred		(72	)		—			(72	)
Ending balance at March 31, 2011	$	5,257		$	6,802		$	12,059
Adjustments to estimated fair value		(924	)		(4,458	)		(5,382	)
Ending balance at June 30, 2011	$	4,333		$	2,344		$	6,677