Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Significant components deferred tax assets

Significant components of the Company’s deferred tax assets as of December 31, 2016, 2015 and 2014 are listed below (in thousands):

	December 31,
	2016			2015			2014
Deferred tax assets:
Capitalized research and development and other	$	9,380		$	33,894		$	31,045
Valuation allowance for deferred tax assets	(9,380		)	(33,894		)	(31,045		)
Net deferred taxes	$	—		$	—		$	—

Provision for income taxes

Income taxes computed by applying the U.S. federal statutory rates to income from continuing operations before income taxes are reconciled to the provision for income taxes set forth in the statement of operations as follows (in thousands):

	December 31,
	2016			2015			2014
Income tax benefit at statutory federal rate	$	(26,583	)	$	(14,250	)	$	(7,256	)
Research and development credits	(1,240		)	1,128			991
Expired tax attributes	(5		)	31			(60		)
Change in valuation allowance	25,091			12,042			6,322
Other	2,737			1,049			3
Provision for income taxes	$	—		$	—		$	—