Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation

The reconciliation of the U.S. income tax rate to the effective income tax rate for continuing operations is as follows:

	AS OF DECEMBER 31,
	2013		2014
Statutory tax rate	35.00	%	35.00	%
Effect of:
State income taxes net of federal tax benefit	—		—
Permanent differences	(2.41	)	(5.09	)
Corrections to deferred assets	—		—
Other	0.35		—
General business credits	5.41		2.02
Change in valuation allowance	(38.35	)	(31.93	)
Effective tax rate	—	%	—	%

Schedule of Deferred Tax Assets and Liabilities

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

	AS OF DECEMBER 31,
	2013			2014
Deferred tax assets:
Net operating loss carryforwards	$	18,898		$	29,052
Research and development credit	1,969			2,658
Depreciation and amortization	174			174
Other temporary differences	232			292
Gross deferred tax assets	21,273			32,176
Deferred tax asset valuation allowance	(21,273		)	(32,176		)
Net deferred tax assets	$	—		$	—