Securities Purchase Agreement (Tables)

12 Months Ended

Dec. 31, 2012

Securities Purchase Agreement [Abstract]

Fair values of derivative liabilities

The estimated fair values of the Derivative Liabilities as of December 31, 2011 are summarized as follows (in thousands): 

	Fair Value Measurements at
	December 31, 2012		December 31, 2011
Embedded Derivatives of Series C-12 Stock (including dividends paid in Series C-12Stock)	$	—	$	3,628
Embedded Derivatives of accrued dividends payable in Series C-12 Stock	—		52
Series D-12 Warrants	—		2,539
Series C-22 Warrants for:
Series C-22 Stock	—		3,785
Series D-22 Warrants	—		5,266
	$	—	$	15,270

Embedded Derivatives

The Embedded Derivatives were valued at December 31, 2011 using a binomial option pricing model, based on the value of the Series C-1² Stock with and without embedded derivative features, with the following assumptions:

	December 31, 2012		December 31, 2011
Closing price per share of Common Stock	$	—	$	0.27
Conversion price per share	$	—	$	0.60
Volatility	—		88.0		%
Risk-free interest rate	—		0.83		%
Credit spread	—		20.9		%
Remaining expected lives of underlying securities (years)	0		5.0

Series D1 warrants using binomial option pricing

The Series D-1² Warrants were valued at December 31, 2011 using a binomial option pricing model with the following assumptions: 

	December 31, 2012		December 31, 2011
Closing price per share of Common Stock	$	—	$	0.27
Conversion price per share	$	—	$	0.60
Volatility	—		67.5		%
Risk-free interest rate	—		0.28		%
Remaining expected lives of underlying securities (years)	0		2.2
Probability of Strategic Transaction	—		70		%

Series C2 warrants using binomial option pricing

The portion of the Series C-2² Warrants that represent the rights to purchase Series C-2² Stock were valued at December 31, 2011 using a binomial option pricing model, discounted for the lack of dividends until the Series C-2² Warrants are exercised, with the following assumptions:

	December 31, 2012		December 31, 2011
Closing price per share of Common Stock	$	—	$	0.27
Conversion price per share	$	—	$	0.60
Volatility	—		88.0		%
Risk-free interest rate	—		0.83		%
Credit spread	—		20.9		%
Remaining expected lives of underlying securities (years)	0		5.0
Time to Exercise (months)	0		24