Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Components of (Loss) Income before (Provision) Benefit for Income Taxes

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

	For the Years Ended December 31,
	2018			2017			2016
United States	$	(125,177	)	$	(109,678	)	$	(69,976	)
Foreign	5,167			1,652			(2,107		)
Total	$	(120,010	)	$	(108,026	)	$	(72,083	)

Provision (Benefit) for Income Taxes

The provision (benefit) for income taxes consist of the following:

	For the Years Ended December 31,
	2018			2017			2016
Current:
Federal	$	(11	)	$	(10,608	)	$	(2,001	)
State	(19		)	(940		)	(216		)
Foreign	—			7			8
	$	(30	)	$	(11,541	)	$	(2,209	)
Deferred:
Federal	12			(5,256		)	(93		)
State	19			19			(11		)
Foreign	—			—			—
	31			(5,237		)	(104		)
Total income tax provision (benefit)	$	1		$	(16,778	)	$	(2,313	)

Income Tax Provision (Benefit) Differs from Computed Using Federal Statutory Rate Applied to Income before Taxes

The income tax provision (benefit) differs from that computed using the applicable federal statutory rate, as applied to income before taxes in each year as follows:

	For the Years Ended December 31,
	2018			2017			2016
Tax provision computed at the federal statutory rate	$	(25,202	)	$	(37,809	)	$	(25,217	)
State tax, net of federal benefit	(4,827		)	(1,849		)	(307		)
Research credits	(4,884		)	(1,176		)	(3,232		)
Change in tax credit carryforwards	(3,056		)	386			11,042
Officers compensation	600			(9,292		)	1,196
Stock based compensation	(12,610		)	(2,735		)	588
Permanent items and other	(116		)	1,450			12
Tax differential on foreign earnings	(32		)	33			15
Change in tax rate	(1,329		)	37,769			(744		)
Refundable ATM credit	—			(1,336		)	—
Uncertain tax positions	—			(561		)	—
Change in prior year deferred taxes	6,595			(1,218		)	—
Valuation allowance	44,862			(440		)	14,334
Income tax provision (benefit)	$	1		$	(16,778	)	$	(2,313	)

Components of Company's Deferred Tax Assets

Significant components of our deferred tax assets and liabilities as of December 31, 2018 and 2017 are presented below. A valuation allowance has been recognized to offset the net deferred tax assets as realization of such deferred tax assets did not meet the “more-likely-than-not” threshold under GAAP.

	December 31,
	2018			2017
Deferred tax assets:
Net operating loss carry forwards	$	106,446		$	60,771
Research credits	21,618			14,255
Stock based compensation	5,057			10,046
Deferred revenue	—			1,017
Development costs	3,938			4,143
Returns and allowances	1,976			1,636
Other, net	(5,066		)	—
Total deferred tax assets before valuation allowance	133,969			91,868
Valuation allowance	(131,042		)	(86,021		)
Total deferred tax assets	2,927			5,847
Deferred tax liabilities:
Basis difference in debt	—			(28		)
Depreciation and amortization differences	(4,396		)	(6,836		)
Other, net	—			(421		)
Net deferred tax liabilities	$	(1,469	)	$	(1,438	)

Summary of Unrecognized Tax Benefits

The following tabular reconciliation summarizes activity related to unrecognized tax benefits:

	For the Years Ended December 31,
	2018			2017			2016
Balance at beginning of year	$	2,715		$	3,271		$	4,498
Adjustments related to prior year tax positions	(551		)	(39		)	(1,638		)
Increases related to current year tax positions	1,084			374			411
Decreases due to expiration of tax statutes	—			(891		)	—
Balance at end of year	$	3,248		$	2,715		$	3,271