Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Summary of (loss) before income taxes

	Year ended December 31,
	2017			2016
	(in thousands)
U.S.	$	(17,104	)	$	(50,689	)
Foreign		(659	)		(12,413	)
Total	$	(17,763	)	$	(63,102	)

Summary of income tax expense (benefit)

	Year ended December 31,
	2017		2016
	(in thousands)
Current
U.S.	$	—	$	—
State		—		—
Foreign		88		331
Total current income tax expense		88		331
Deferred
U.S.		—		—
State		—		—
Foreign		—		(554	)
Total deferred income tax expense (benefit)		—		(554	)
Total income tax expense (benefit)	$	88	$	(223	)

Summary of reconciliation of income tax computed at federal statutory rate to income before taxes

	Year ended December 31,
	2017			2016
U.S. Federal statutory rate		(33.6	)%		(34.0	)%
State taxes net of federal benefit		(4.9	)		(4.1	)
Impact of new federal tax rate		157.8			—
Foreign rate differential and transactional tax		0.3			1.8
Impact of foreign tax holiday		—			(0.9	)
Valuation allowance		(118.4	)		36.6
Other		(0.7	)		0.2
		0.5	%		(0.4	)%

Summary of significant components of net deferred income taxes

	2017			2016
	(in thousands)
Deferred tax assets:
Allowance for doubtful accounts	$	2		$	12
Inventory reserves		3,672			3,855
Accrued liabilities		4			11
Warrant interest expense		196			269
Stock compensation expense		2,022			2,774
State net operating loss—net of tax		15,954			9,189
Net operating loss carryforward		37,856			50,284
Tax credits		999			825
Depreciation		5,117			4,995
Valuation allowance		(65,817	)		(72,199	)
Total deferred tax assets		5			15
Deferred tax liability:
Prepaid expenses		(5	)		(15	)
Net deferred tax liability	$	—		$	—

Summary of reconciliation of unrecognized tax benefit

Balance at December 31, 2016	$	1,141
Decrease related to prior year positions		—
Tax position related to current year		—
Balance at December 31, 2017	$	1,141