Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Income Tax Disclosure [Abstract]

Loss Before Income Taxes

Loss before income taxes for the years ended December 31 consisted of the following:

	2013			2012			2011
	(In thousands)
Domestic	$	(28,746	)	$	(17,618	)	$	(10,966	)
Foreign		(535	)		(90	)		34
Loss before income taxes	$	(29,281	)	$	(17,708	)	$	(10,932	)

Income Tax Expense (Benefit) Differed from Amounts Computed by Applying Statutory Federal Income Tax Rate

Income tax expense (benefit) differed from the amounts computed by applying the statutory federal income tax rate of 34% to pretax loss as a result of the following for the years ended December 31:

	2013			2012			2011
	(In thousands)
Income tax provision at statutory rate	$	(9,955	)	$	(6,021	)	$	(3,717	)
Nondeductible items		(32	)		349			25
Change in tax credits		(893	)		39			(202	)
Change in valuation allowance		10,965			5,894			3,963
Other		(85	)		(261	)		(69	)
	$	—		$	—		$	—

Effect of Temporary Differences and Carryforwards

The effect of temporary differences and carryforwards that give rise to deferred tax assets for the years ended December 31 were as follows:

	2013			2012
	(In thousands)
Net operating loss carryforwards	$	31,989		$	21,569
Research and development tax credit carryforwards		1,654			761
Other		2,369			2,717
Total deferred tax assets		36,012			25,047
Less: Valuation allowance		(36,012	)		(25,047	)
Net deferred tax assets	$	—		$	—

Summary of Changes in Deferred Tax Asset Valuation Allowance

The table below summarizes changes in the deferred tax asset valuation allowance:

	Balance at Beginning of Year		Charged to Costs and Expenses		Write-offs		Balance at End of Year
	(In thousands)
Deferred tax valuation allowance:
For year ended December 31, 2011	$	15,190	$	3,963	$	—	$	19,153
For year ended December 31, 2012		19,153		5,894		—		25,047
For year ended December 31, 2013		25,047		10,965		—		36,012

Total Balance of Unrecognized Gross Tax Benefits

The total balance of unrecognized gross tax benefits for the years ended December 31 was as follows:

	2013		2012			2011
	(In thousands)
Unrecognized tax benefits at beginning of year	$	253	$	267		$	199
Additions (reductions) based on current year tax positions		298		(14	)		68
Unrecognized tax benefits at end of year	$	551	$	253		$	267