Notes Payable (Tables)

12 Months Ended

Dec. 31, 2013

Summary of Notes Payable

Notes payable, net of related discounts, consists of the following:

	December 31,
	2013		2012
	(in thousands)
Amended and Restated Convertible Notes	$	32,230	$	31,576
Amended and Restated Reimbursement Notes		556		600
Amended and Restated Bridge Notes		293		1,431
		33,079		33,607
Less: Current portion		556		33,607
Non-current Notes payable, net of related discounts	$	32,523	$	—

Statements of Fair Value Assumptions

The assumptions used by the Company are summarized below:

Amended and Restated August 2009 Warrants

	Immediately Before			Immediately After
Closing stock price	$	0.24		$	0.23
Conversion price	$	0.70		$	0.50
Expected volatility		175.71	%		143.31	%
Remaining term (years)		1.29			6.17
Risk-free rate		0.11	%		1.21	%
Expected dividend yield		0	%		0	%

Amended and Restated June 2010 Warrants

	Immediately Before			Immediately After
Closing stock price	$	0.24		$	0.23
Conversion price	$	2.90		$	0.50
Expected volatility		185.0	%		145.0	%
Remaining term (years)		1.29			6.17
Risk-free rate		0.14	%		1.01	%
Expected dividend yield		0	%		0	%

Amended and Restated August 2010 Warrants

	Immediately Before			Immediately After
Closing stock price	$	0.24		$	0.23
Conversion price	$	1.26		$	0.50
Expected volatility		182.34			143.31	%
Remaining term (years)		2.31			6.17
Risk-free rate		0.22	%		1.21	%
Expected dividend yield		0	%		0	%

Amended and Restated July 2011 Warrants

	Immediately Before			Immediately After
Closing stock price	$	0.24		$	0.23
Conversion price	$	1.09		$	0.50
Expected volatility		174.11			143.31	%
Remaining term (years)		3.17			6.17
Risk-free rate		0.36	%		1.21	%
Expected dividend yield		0	%		0	%

MHR Restructuring Warrants

	Immediately Before		Immediately After
Closing stock price	$	—	$	0.23
Conversion price	$	—	$	0.50
Expected volatility		—		143.31	%
Remaining term (years)		—		6.17
Risk-free rate		—		1.21	%
Expected dividend yield		—		0	%

Estimated Fair Value of Warrants

The estimated fair value of the warrants immediately before and after the modification is as follows:

	Immediately Before		Immediately After
	(in thousands)
Amended and Restated August 2009 Warrants	$	445	$	768
Amended and Restated June 2010 Warrants	$	152	$	294
Amended and Restated August 2010 Warrants	$	570	$	741
Amended and Restated July 2011 Warrants	$	696	$	783
MHR Restructuring Warrants	$	—	$	2,058

Book Value of MHR Convertible Notes

The carrying value of the MHR Obligations is comprised of the following:

	December 31,
	2013			2012
	(in thousands)
Amended and Restated Convertible Notes	$	35,935		$	31,576
Amended and Restated Reimbursement Notes		637			600
Amended and Restated Bridge Notes		1,627			1,431
Unamortized discounts		(5,120	)		—
	$	33,079		$	33,607

Amended and Restated Convertible Notes [Member]

Statements of Fair Value Assumptions

Amended and Restated Convertible Notes

	May 7, 2013
Closing stock price	$	0.23
Conversion price	$	1.25
Expected volatility		160	%
Remaining term (years)		4.39
Risk-free rate		0.63	%
Expected dividend yield		0	%

Amended and Restated Reimbursement Notes [Member]

Statements of Fair Value Assumptions

Amended and Restated Reimbursement Notes

	May 7, 2013
Closing stock price	$	0.23
Conversion price	$	0.50
Expected volatility		184	%
Remaining term (years)		0.97
Risk-free rate		0.15	%
Expected dividend yield		0	%

Amended and Restated Bridge Notes [Member]

Statements of Fair Value Assumptions

Amended and Restated Bridge Notes

	May 7, 2013
Closing stock price	$	0.23
Conversion price	$	0.50
Expected volatility		160	%
Remaining term (years)		4.39
Risk-free rate		0.63	%
Expected dividend yield		0	%