Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Components of Loss Before Income Taxes

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

	Year Ended December 31,
	2018			2017
Domestic	$	(13,470	)	$	(15,681	)
Foreign		—			—
Loss before income taxes	$	(13,470	)	$	(15,681	)

Schedule of Income Tax Expense Comprised of Current State Taxes and Foreign Taxes

The total income tax expense for the years ended December 31, 2018 and 2017 was $10,000 and $26,000, respectively, and is comprised of current state taxes and foreign taxes withheld by governmental agencies outside of the United States, as follows (in thousands):

	Year Ended December 31,
	2018		2017
Current:
Federal	$	—	$	—
State		1		2
Foreign		9		24
Total current tax expense		10		26
Deferred:
Federal		—		—
State		—		—
Foreign		—		—
Total deferred tax benefit		—		—
Total tax expense	$	10	$	26

Reconciliation of the Statutory Federal Income Tax Rate

The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate is as follows:

	Year Ended December 31,
	2018			2017
Expected income tax provision at the federal    statutory rate		21.0	%		34.0	%
State taxes, net of federal benefit		8.5	%		2.6	%
Change in valuation allowance		(27.3	)%		91.4	%
Transaction costs		(2.9	)%		—
Related offering costs		(1.1	)%		—
Excess windfall benefit		1.4	%		—
Nondeductible expenses		—			0.1	%
Impact of change in federal tax rate		—			(124.6	)%
Withholding taxes		(0.1	)%		(0.2	)%
Other		0.4	%		(3.5	)%
Income tax provision		(0.1	)%		(0.2	)%

Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands)

	As of December 31,
	2018			2017
Deferred tax assets:
Net operating loss carryforwards	$	42,097		$	37,498
Unearned revenue		26			783
Stock-based compensation		2,855			2,273
Accrued payroll and benefits		255			51
Research and development credits		171			171
Fixed asset basis difference		114			128
Inventory reserve		508			396
Charitable contributions		3			3
Total deferred tax assets		46,029			41,303
Deferred tax liabilities:
Common stock warrant liabilities		(1,529	)		—
Total deferred tax liabilities		(1,529	)		—
Less valuation allowance		(44,500	)		(41,303	)
Net deferred tax assets	$	—		$	—