Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Components of Loss Before Provision for Income Taxes

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

	Year Ended December 31,
	2020		2019		2018
United States	$	49,973	$	(1,266,677)	$	(31,641)
Foreign	(176,993)		(94,162)		(30,923)
Loss before provision for income taxes	$	(127,020)	$	(1,360,839)	$	(62,564)

Composition of the Provision for Income Taxes

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

	Year Ended December 31,
	2020		2019		2018
Current:
Federal	$	—	$	—	$	—
State	79		—		—
Foreign	691		1,677		500
Total current tax expense	770		1,677		500
Deferred:
Federal	654		(555)		4
State	5		(76)		4
Foreign	(126)		(514)		(98)
Total deferred tax expense (benefit)	533		(1,145)		(90)
Provision for income taxes	$	1,303	$	532	$	410

Reconciliation of the Difference Between Income Taxes Computed at the Statutory Federal Income Tax Rate and the Provision for Income Taxes

The difference between income taxes computed at the statutory federal income tax rate and the provision for income taxes is attributable to the following (in thousands):

	Year Ended December 31,
	2020		2019		2018
Tax at U.S. statutory rate	$	(26,674)	$	(285,776)	$	(13,138)
State income taxes, net of benefit	84		(77)		4
Foreign losses not benefited	37,716		20,932		6,891
Permanent book/tax differences	1,051		2,453		1,967
Legal settlement	2,290		—		—
Share-based compensation	(303,245)		(84,366)		(864)
Change in valuation allowance	352,410		422,315		15,952
Tax credits	(63,205)		(74,399)		(10,460)
Other	876		(550)		58
Provision for income taxes	$	1,303	$	532	$	410

Significant Components of Deferred Tax Assets and Liabilities

Significant components of our deferred tax assets and liabilities are as follows (in thousands):

	December 31,
	2020		2019
Deferred tax assets:
Net operating loss carryforwards	$	784,721	$	416,709
Research tax credits	269,658		167,489
Reserves, accruals, and other	18,106		15,960
Lease obligation	44,446		52,734
Share-based compensation	96,932		133,067
Total deferred tax assets	1,213,863		785,959
Less: valuation allowance	(1,176,910)		(737,003)
Deferred tax assets, net of valuation allowance	36,953		48,956
Deferred tax liabilities:
Depreciation and amortization	(34,576)		(46,398)
Prepaid expenses	(1,523)		(1,862)
Total deferred tax liabilities	(36,099)		(48,260)
Net deferred tax assets	$	854	$	696

Changes in Gross Unrecognized Tax Benefits

Changes in gross unrecognized tax benefits were as follows (in thousands):

	Gross Unrecognized Tax Benefits
Balance as of December 31, 2018	$	38,550
Decreases for tax positions of prior years	(50)
Increases for tax positions of current year	90,685
Balance as of December 31, 2019	$	129,185
Increases for tax positions of prior years	886
Decreases for tax positions of prior years	(37,250)
Increases for tax positions of current year	47,339
Balance as of December 31, 2020	$	140,160