Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Taxes

Summary of Components of the Provision for Income Taxes

The components of the provision for income taxes for the year ended December 31, 2019, 2018 and 2017, are as follows (in thousands):

	Year Ended December 31,
	2019		2018		2017
Current:
State	$	2	$	4	$	5
Foreign		301		—		1,204
Total current		303		4		1,209
Deferred:
Federal		—		—		(30)
Total deferred		—		—		(30)
Provision for income taxes	$	303	$	4	$	1,179

Reconciliation of Statutory Federal Income Tax Rate to the Company's Effective Tax Rate

	Year Ended December 31,
	2019		2018		2017
Change in valuation allowance	(21.9)	%	(22.5)	%	19.9	%
Income tax at the federal statutory rate	21.0		21.0		35.0
State taxes, net of federal benefit	0.3		0.6		0.5
Net impact related to foreign subsidiary	—		—		(1.2)
Impact of tax reform rate change	—		—		(56.4)
Tax credits	1.6		1.4		1.0
Stock based compensation	(0.9)		(1.2)		(0.8)
Other	(0.4)		0.7		0.1
Income tax provision	(0.3)	%	—	%	(1.9)	%

Significant Components of the Company's Deferred Tax Assets

	December 31,
	2019		2018
	(in thousands)
Deferred tax assets:
Amortization and depreciation	$	45,555	$	38,376
Net operating loss carryforwards		40,896		31,621
Tax credits		10,136		8,200
Stock-based compensation		4,853		3,763
Lease obligation		984		—
Other		940		888
Gross deferred tax assets		103,364		82,848
Valuation allowance		(102,344)		(81,645)
Deferred tax assets net of valuation allowance		1,020		1,203
Deferred tax liabilities
Right of use asset		(834)		—
Revenue recognition		(158)		(1,054)
Other		(28)		(149)
Net deferred tax assets	$	—	$	—

Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits

	December 31,
	2019		2018		2017
	(in thousands)
Balance at beginning of year	$	23,052	$	20,734	$	3,892
Additions based on tax positions related to prior year		755		1,634		16,103
Additions based on tax positions related to current year		731		684		739
Balance at end of year	$	24,538	$	23,052	$	20,734