Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

	Year Ended December 31,
	2014		2013			2012
Current provision (benefit):
Federal	$	—	$	(49	)	$	(128	)
State	41		4			51
Total current provision (benefit)	41		(45		)	(77		)
Deferred provision:
Federal	18		—			—
State	3		—			—
Total deferred provision	21		—			—
Total income tax provision (benefit)	$	62	$	(45	)	$	(77	)

Schedule of Net Deferred Tax Assets

net deferred tax assets (liabilities) consisted of the following (in thousands):

	December 31,
	2014			2013
Deferred tax assets (liabilities):
Net operating loss carryforwards	$	33,732		$	34,727
Research and development and other credits	1,950			1,928
Reserves	1,417			1,273
Intangibles	2,097			2,425
Other, net	1,079			830
Total deferred tax assets	40,275			41,183
Deferred tax liabilities—depreciation	(237		)	(300		)
Valuation allowance for deferred tax assets	(40,059		)	(40,883		)
Net deferred tax assets (liabilities)	$	(21	)	$	—

Schedule of Effective Income Tax Rate Reconciliation

	Year Ended December 31,
	2014		2013		2012
Income tax expense (benefit) at statutory federal rate	35.0	%	35.0	%	(35.0	)%
State income tax expense (benefit), net of federal benefit	4.8	%	7.2	%	(2.9	)%
Permanent differences and other	(2.9	)%	14.8	%	1.4	%
Research and development credits, current year	—	%	(58.1	)%	(2.6	)%
Research and development credits, prior year	—	%	(39.1	)%	—	%
Change in effective state tax rates	(3.2	)%	(25.6	)%	2.4	%
Expiration of net operating loss carryovers	1.1	%	8.2	%	36.6	%
Stock compensation expense	0.1	%	53.7	%	—	%
Reserve for uncertain tax positions and other reserves	—	%	5.4	%	(2.4	)%
Change in valuation allowance	(32.5	)%	(22.2	)%	1.0	%
Provision (benefit) for income taxes	2.4	%	(20.7	)%	(1.5	)%

Schedule of Unrecognized Tax Benefits Roll Forward

The following table summarizes the activity related to our unrecognized tax benefits (in thousands):

	December 31,
	2014		2013			2012
Balance at beginning of year	$	1,553	$	1,539		$	1,621
Increases related to prior year tax positions	—		5			25
Increases related to current year tax positions	—		64			81
Expiration of the statute of limitations for the assessment of taxes	—		(55		)	(252		)
Change in valuation allowances	—		—			64
Balance at end of year	$	1,553	$	1,553		$	1,539