Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of Income Before Income Tax, Domestic and Foreign

Income (loss) before provision for income taxes includes the following components (in thousands):

	Year Ended December 31,
	2021		2020		2019
Domestic	$	(524,440)	$	(445,370)	$	(441,494)
Foreign	1,160		1,423		1,440
Loss before provision for income taxes	$	(523,280)	$	(443,947)	$	(440,054)

Schedule of Provision for Income Taxes

The provision for income taxes consists of the following (in thousands):

	Year Ended December 31,
	2021		2020		2019
Current:
Federal	$	—	$	—	$	—
State	50		165		139
Foreign	609		364		495
Total current income tax expense	659		529		634
Deferred:
Federal	—		—		—
State	—		—		—
Foreign	(102)		(36)		(21)
Total deferred income tax expense	(102)		(36)		(21)
Provision for income taxes	$	557	$	493	$	613

Schedule of Income Tax Provision Related to Continuing Operations

Our income tax provision related to continuing operations differs from the amount computed by applying the statutory income tax rate of 21% to our pretax loss as follows (in thousands):

	Year Ended December 31,
	2021		2020		2019
Income tax benefit at federal statutory rate	$	(109,889)	$	(93,229)	$	(92,411)
Research credits	(4,727)		(3,081)		(10,511)
Change in valuation allowance	97,914		87,060		104,440
Non-cash interest expense on liability related to sales of future royalties	9,936		6,356		5,259
Non-cash royalty revenue related to sales of future royalties	(7,891)		(7,967)		(7,624)
Loss on revaluation of liability related to the sale of future royalties	4,940		—		—
Stock-based compensation	6,627		7,929		(672)
Other	3,647		3,425		2,132
Provision for income taxes	$	557	$	493	$	613

Schedule of Significant Components of Deferred Tax Assets and Liabilities

We measure deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future. Significant components of our deferred tax assets for federal and state income taxes are as follows (in thousands):

	December 31,
	2021		2020
Deferred tax assets:
Net operating loss carryforwards	$	564,712	$	456,284
Research and other credits	139,996		132,994
Operating lease liabilities	34,680		35,672
Stock-based compensation	33,408		32,517
Liability related to the sale of future royalties	23,757		32,737
Development derivative liability	6,639		—
Other	10,651		11,688
Deferred tax assets before valuation allowance	813,843		701,892
Valuation allowance for deferred tax assets	(785,748)		(670,103)
Total deferred tax assets	28,095		31,789
Deferred tax liabilities:
Operating lease right-of-use assets	(27,204)		(29,707)
Other	(564)		(1,856)
Total deferred tax liabilities	(27,768)		(31,563)
Net deferred tax assets	$	327	$	226

Schedule of Unrecognized Tax Benefits

We have the following activity relating to unrecognized tax benefits (in thousands):

	Year Ended December 31,
	2021		2020		2019
Beginning balance	$	78,665	$	77,410	$	27,419
Tax positions related to current year:
Additions	2,371		2,512		49,858
Reductions	—		—		—
Tax positions related to prior years:
Additions	58		193		277
Reductions	(490)		(1,450)		(144)
Settlements	—		—		—
Lapses in statute of limitations	—		—		—
Ending balance	$	80,604	$	78,665	$	77,410