Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Loss Before Income Taxes

Loss before income taxes for the years ended December 31 consisted of the following (in thousands):

	2021		2020		2019
Domestic	$	(116,178)	$	(111,101)	$	(41,720)
Foreign	1,091		1,276		1,293
Loss before income taxes	$	(115,087)	$	(109,825)	$	(40,427)

Significant Components of our Provision for Income Taxes

Significant components of our provision for income taxes for the years ended December 31 are as follows (in thousands):

	2021		2020		2019
Current:
Domestic	$	—	$	—	$	—
Foreign	167		253		269
Total provision for income taxes	$	167	$	253	$	269

Income Tax Expense (Benefit) Differed from Amounts Computed by Applying Statutory Federal Income Tax Rate

A reconciliation of the federal statutory income tax rate to the effective income tax rate for the years ended December 31 are as follows (in thousands):

	2021		2020		2019
Income tax provision at federal statutory rate	$	(24,168)	$	(23,063)	$	(8,490)
Tax on repatriated foreign earnings and other nondeductible items	580		348		403
Section 162(m) limitations	5,824		5,044		1,438
Change in tax credits	(2,514)		3,123		(3,738)
Change in valuation allowance	36,550		21,766		17,842
Changes in federal and state tax rates	(110)		586		(4,058)
Stock option exercise windfall	(9,761)		(7,683)		(1,763)
RTP and other true-ups	(2,823)		2,461		(485)
State and foreign tax, and other	(3,411)		(2,329)		(880)
Total provision for income taxes	$	167	$	253	$	269

Effect of Temporary Differences and Carryforwards

The effect of temporary differences and carryforwards that give rise to deferred tax assets and liabilities for the years ended December 31 were as follows (in thousands):

	2021		2020
Deferred tax assets:
Net operating loss carryforwards	$	131,971	$	100,927
Research and development tax credit carryforwards	12,028		9,513
Operating lease liability	6,423		6,962
Stock-based compensation	6,287		5,221
Foreign tax credit carryforwards	659		648
Accruals and other	10,139		8,138
Total deferred tax assets before allowance	167,507		131,409
Less: Valuation allowance	(162,817)		(114,335)
Deferred tax assets, net	4,690		17,074
Deferred tax liabilities:
Right of use asset and other	(4,690)		(5,029)
Debt discount (equity component)	—		(12,045)
Deferred tax liability	(4,690)		(17,074)
Net deferred tax assets and liabilities	$	—	$	—

Summary of Changes in Deferred Tax Asset Valuation Allowance

The table below summarizes changes in the deferred tax asset valuation allowance for the years ended December 31 (in thousands):

	2021		2020		2019
Balance at beginning of year	$	114,335	$	106,438	$	88,596
Impact of adoption of ASU 2020-06 on debt discount (equity component) deferred tax liability	11,932		—		—
Charged to costs and expenses	36,440		8,483		13,784
Impact of change in tax rate	110		(586)		4,058
Balance at end of year	$	162,817	$	114,335	$	106,438

Total Balance of Unrecognized Gross Tax Benefits Resulting from R&D Credits Claimed

The total balance of unrecognized gross tax benefits for the years ended December 31, resulting from research and development tax credits claimed on the Company’s annual tax return was as follows (in thousands):

	2021		2020		2019
Unrecognized tax benefits at beginning of year	$	9,171	$	4,212	$	2,830
Additions based on current year tax positions	838		4,959		1,382
Unrecognized tax benefits at end of year	$	10,009	$	9,171	$	4,212