Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

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,
	2017		2016
Statutory tax rate	35.0	%	35.0	%
Effect of:
Permanent differences	(6.4	)	(1.5	)
Other	(0.5	)	(0.4	)
General business credits	15.1		2.4
Change in valuation allowance	15.6		(35.5	)
Tax Reform - tax rate change	(58.8	)	—
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,
	2017			2016
Deferred tax assets:
Net operating loss carryforwards	$	39,971		$	52,154
Research and development credit	13,392			5,582
Depreciation and amortization	1,241			2,023
Other temporary differences	4,477			6,154
Gross deferred tax assets	59,081			65,913
Deferred tax asset valuation allowance	(59,081		)	(65,913		)
Net deferred tax assets	$	—		$	—