Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Loss Before Income Taxes

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

	2014			2013			2012
	(In thousands)
Domestic	$	(50,455	)	$	(28,746	)	$	(17,618	)
Foreign		417			(535	)		(90	)
Loss before income taxes	$	(50,038	)	$	(29,281	)	$	(17,708	)

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:

	2014			2013			2012
	(In thousands)
Income tax provision at statutory rate	$	(17,013	)	$	(9,955	)	$	(6,021	)
Nondeductible items		456			(32	)		349
Change in tax credits		(678	)		(893	)		39
Change in valuation allowance		17,911			10,965			5,894
Other		(676	)		(85	)		(261	)
	$	—		$	—		$	—

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:

	2014			2013
	(In thousands)
Net operating loss carryforwards	$	47,444		$	31,989
Research and development tax credit carryforwards		2,332			1,654
Other		4,147			2,369
Total deferred tax assets		53,923			36,012
Less: Valuation allowance		(53,923	)		(36,012	)
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		Changed to Costs and Expenses		Write-offs		Balance at End of Year
	(In thousands)
Deferred tax valuation allowance:
For year ended December 31, 2012	$	19,153	$	5,894	$	—	$	25,047
For year ended December 31, 2013		25,047		10,965		—		36,012
For year ended December 31, 2014		36,012		17,911		—		53,923

Total Balance of Unrecognized Gross Tax Benefits Resulting from R&D Credits Claimed

The total balance of unrecognized gross tax benefits for the years ended December 31, resulting from R&D credits claimed on the Company’s annual tax return was as follows:

	2014		2013		2012
	(In thousands)
Unrecognized tax benefits at beginning of year	$	551	$	253	$	267
Additions (reductions) based on current year tax positions		226		298		(14	)
Unrecognized tax benefits at end of year	$	777	$	551	$	253