Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of components of loss before provision for income taxes

The components of loss before provision for income taxes were as follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
	(in thousands)
United States	$	(69,930	)	$	(84,313	)	$	(83,214	)
Foreign	207			88			—
Total	$	(69,723	)	$	(84,225	)	$	(83,214	)

Schedule of components of the provision for income taxes

The components of the provision for income taxes are as follows:

	Year Ended December 31,
	2019			2018		2017
	(in thousands)
Current:
State	$	3		$	4	$	—
Foreign	266			34		7
Total current tax expense	$	269		$	38	$	7
Deferred:
Federal	$	(1,652	)	$	—	$	—
State	(311		)	—		—
Foreign	(178		)	—		—
Total deferred tax expense	$	(2,141	)	$	—	$	—
Total provision for income taxes	$	(1,872	)	$	38	$	7

Schedule of the components of deferred tax assets and liabilities

Significant components of the Company’s deferred tax assets are as follows:

	Year Ended December 31,
	2019			2018
	(in thousands)
Deferred tax assets:
Net operating losses carryforwards	$	90,534		$	36,783
Intangible assets	14,165			17,107
Accruals and reserves	4,936			5,127
Research and development credits	11,031			5,753
Stock-based compensation	3,143			1,289
Lease liabilities	10,195			—
Other	160			210
Total deferred tax asset	$	134,164		$	66,269
Deferred tax liabilities:
Property and equipment	$	(119	)	$	(73	)
Section 481 (a) adjustment	(914		)	—
Right-of-use asset	(7,363		)	—
Unrealized gain/loss on investments	(346		)	—
Less: valuation allowance	(125,245		)	(66,196		)
Net deferred tax assets	$	177		$	—

Effective tax rate reconciliation

The following table presents a reconciliation of the income tax expense computed at the statutory federal rate and the Company’s income tax expense for the periods presented:

	Year Ended December 31,
	2019			2018			2017
	(in thousands)
Tax at the statutory federal rate	$	(14,642	)	$	(17,690	)	$	(28,293	)
Other nondeductible items	887			329			371
Stock-based compensation	(33,042		)	497			3,819
Research and development credits	(5,266		)	(1,726		)	(714		)
Change in valuation allowance	59,049			22,516			5,415
State taxes, net of federal benefits	(8,253		)	(4,231		)	(1,868		)
Change in tax rate due to Tax Act	—			—			21,346
Other	(605		)	343			(69		)
Total provision for (benefit from) income taxes	$	(1,872	)	$	38		$	7

Reconciliation of the balance of total gross unrecognized tax benefits

A reconciliation of the beginning and ending balance of total unrecognized tax benefits is as follows:

	Year Ended December 31,
	2019		2018		2017
	(in thousands)
Unrecognized tax benefits - Beginning of period	$	3,427	$	1,712	$	884
Increases related to current year’s tax positions	3,116		1,635		828
Increases related to prior years’ tax positions	—		80		—
Unrecognized tax benefits - End of period	$	6,543	$	3,427	$	1,712