Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of Differences Between Federal Income Tax Rate and Effective Tax Rate

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,
	2019				2018				2017
Expected income tax benefit at the federal statutory rate		21.0		%		21.0		%		34.0		%
State taxes, net of federal benefit		0.0				0.0				0.0
Change in federal statutory rate		0.0				0.0				(54.1	)
Non-deductible items and other		(2.8	)			(0.2	)			0.5
Federal and state credits		0.6				0.7				0.5
Change in valuation allowance		(18.8	)			(21.5	)			19.1
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, 2019 and 2018 (in thousands):

	Year Ended December 31,
	2019			2018
Deferred tax assets
Net operating loss carryforwards	$	101,967		$	76,753
Research and development tax credits		5,872			4,699
Reserves and accruals		5,720			1,444
Operating lease liability		3,088			—
Other		3,422			9,109
Total deferred tax assets		120,069			92,005
Less: Valuation allowance		(117,229	)		(92,005	)
Net deferred tax assets		2,840			—
Deferred tax liabilities
Right-of-use assets		(2,840	)		—
Total deferred tax liabilities		(2,840	)		—
Net deferred tax assets	$	—		$	—

Schedule of Unrecognized Tax Benefits

At December 31, 2019 and 2018, the Company’s unrecognized tax benefits consist of the following (in thousands):

	Year Ended December 31,
	2019			2018
Unrecognized tax benefit, beginning of period	$	1,595		$	1,135
Gross increases — current year tax positions		595			422
Gross increases — prior year tax positions		—			38
Gross decreases — prior year tax positions		(32	)		—
Unrecognized tax benefit, end of period	$	2,158		$	1,595