Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Significant components of our deferred tax assets are as follows (in thousands):

	December 31,
	2013		2012
Deferred tax assets:
Net operating loss carryforwards	$	85,912	$	81,127
Research credit carryforwards		13,481		12,750
Other, net		3,962		4,190
Deferred revenue		2,116		5,749
Total deferred tax assets		105,471		103,816
Valuation allowance		(105,471)		(103,816)
Net deferred tax assets	$	—	$	—

The effective tax rate of our provision (benefit) for income taxes differs from the federal statutory rate as follows (in thousands):

	Year Ending December 31,
	2013		2012		2011
Computed at 34%	$	3,301	$	(5,134)	$	(5,168)
State taxes		213		(234)		(228)
Book gains (losses) not currently benefited		1,656		3,120		(1,264)
Other		(476)		1,901		2,746
Disallowed interest expense		160		1,363		1,457
Income from debt restructuring		—		(1,615)		2,462
Revaluation of warrant liability		(591)		600		—
Research and development credits		(583)		—		—
Non-cash gain from termination of royalty purchase agreement		(3,047)		—		—
Non-cash gain on settlement of long-term debt		(632)		—		—
Total	$	1	$	1	$	5