Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of components of income tax expense (benefit)

The components of loss before provision for (benefit from) income taxes during the three years ended December 31, 2019 consisted of the following:

	Year Ended December 31,
	2019			2018			2017
United States	$	(116,749	)	$	(208,735	)	$	(245,264	)
Foreign	(16,244		)	(12,602		)	(8,973		)
	(132,993		)	(221,337		)	(254,237		)

Schedule of reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations

A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations follows (in thousands):

	Year Ended December 31,
	2019			2018			2017
Income tax benefit using U.S. federal statutory rate	$	(27,918	)	$	(46,464	)	$	(86,426	)
State income taxes, net of federal benefit	(5,486		)	(6,694		)	(5,570		)
Stock-based compensation	4,379			(12		)	(5,909		)
Research and development tax credits	(2,491		)	(3,743		)	(2,468		)
Effect of federal tax law change	—			—			86,035
Other adjustments - ASU 2016-09 adoption	—			—			6,135
Change in the valuation allowance	26,918			49,550			(39,045		)
Convertible note	(128		)	(128		)	47,016
Permanent items	457			883			543
Uncertain Tax Positions	—			—			3,056
Foreign rate differential	3,414			2,649			—
Other	855			3,959			(3,367		)
Income tax expense	$	—		$	—		$	—

Schedule of principal components of the Company's deferred tax assets

The principal components of the Company’s deferred tax assets are as follows (in thousands):

	December 31,
	2019			2018
Deferred tax assets:
NOL carryforwards	$	243,063		$	225,285
Capitalized research and development	4,099			3,919
Research and development credits	9,608			8,380
Interest Expense	2,729			1,125
Accrued expenses	5,342			2,644
Stock-based compensation	14,952			14,377
UNICAP	103			86
Allowance for bad debt	1,832			840
Operating lease liability	1,696			—
Other	119			106
Gross non-current deferred tax assets	283,543			256,762
Valuation allowance	(255,242		)	(228,322		)
Net non-current deferred tax assets	$	28,301		$	28,440
Deferred tax liabilities:
Depreciation	$	(216	)	$	(347	)
Right-of-Use asset	(1,677		)	—
Convertible debt	(26,408		)	(28,093		)
Gross non-current deferred tax liabilities	(28,301		)	(28,440		)
Net non-current deferred tax assets (liabilities)	$	—		$	—

Schedule of unrecognized tax benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows (in thousands):

	Uncertain Tax Position
Balance at December 31, 2018	$	2,239
Decreases related to prior year tax positions	(285		)
Increases related to prior year tax positions	92
Decreases related to current year tax positions	—
Increases related to current year tax positions	517
Balance at December 31, 2019	$	2,563