Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of Differences Between Income Taxes

The following reconciles the differences between income taxes computed at the federal income tax rate and the provision for income taxes:

	Year Ended December 31,
	2016				2015				2014
Expected income tax benefit at the federal    statutory rate		34.0		%	34.0			%		34.0		%
State taxes, net of federal benefit		0.0				(0.8	)			3.7
Change in effective tax rate		0.0				(0.9	)			1.3
Non-deductible items and other		(0.7	)			(0.5	)			0.4
Federal and state credits		0.6				(0.7	)			1.2
Change in valuation allowance		(33.9	)			(31.1	)			(40.6	)
Total		0.0		%		0.0		%		0.0		%

Schedule of Deferred Tax Assets

The principal components of the Company’s net deferred tax assets consisted of the following at December 31, 2016 and 2015 (in thousands):

	Year Ended December 31,
	2016			2015
Net operating loss carryforwards	$	75,036		$	60,979
Research and development tax credits		2,131			1,731
Reserves and accruals		1,791			966
Other		4,594			2,433
Total deferred tax assets		83,552			66,109
Valuation allowance		(83,552	)		(66,109	)
Net deferred tax assets	$	—		$	—

Schedule of Unrecognized Tax Benefits

At December 31, 2016 and 2015, the Company’s unrecognized tax benefits consist of the following:

	Year Ended December 31,
	2016		2015
Unrecognized tax benefit, beginning of period	$	742	$	—
Gross increases — current year tax positions		198		130
Gross decreases — current year tax positions		—		—
Gross increases — prior year tax positions		—		612
Unrecognized tax benefit, end of period	$	940	$	742