Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Income (Loss) before Income Tax Domestic and Foreign

Income (loss) before income taxes was derived from the following jurisdictions:

	2017			2016			2015
U.S.	$	(16,762	)	$	(24,229	)	$	(21,831	)
Switzerland		19			(10	)		1,347
	$	(16,743	)	$	(24,239	)	$	(20,484	)

Summary of Effective Tax Rates Differ from Statutory Income Tax Rates

Effective tax rates differ from statutory income tax rates in the years ended December 31, 2017, 2016 and 2015 as follows:

	2017			2016			2015
Statutory income tax rate		(34.0	)%		(34.0	)%		(34.0	)%
State income taxes		(6.1	)		(6.8	)		(5.7	)
Valuation allowance increase		(102.0	)		35.9			35.2
Effect of foreign operations		—			—			(1.3	)
Change in unused net operating loss and credit carryforwards		(4.0	)		3.7			2.8
Nondeductible items		1.6			1.6			3.9
Impact of Tax Cuts and Jobs Act		144.5			—			—
		0.0	%		0.4	%		0.9	%

Summary of Deferred Tax Assets (Liabilities)

Deferred tax assets (liabilities) as of December 31, 2017 and 2016 consist of the following:

	2017			2016
Gross deferred tax assets:
Net operating loss carryforward – U.S.	$	43,046		$	58,206
Net operating loss carryforward – Switzerland		67			65
Research and development tax credit carryforward		6,153			5,477
Deferred revenue		339			438
Stock-based compensation		1,882			2,678
Inventory reserve		140			364
Compensation accruals		662			996
Other		575			378
		52,864			68,602
Gross deferred tax liabilities – depreciation and amortization		(826	)		(844	)
Less valuation allowance		(52,038	)		(67,758	)
Net deferred tax asset	$	—		$	—