Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Components of Loss Before Provision for Income Taxes

The components of loss before provision for income taxes were as follows (in thousands):

	Years Ended December 31,
		2017			2016			2015
United States	$	(33,268	)	$	(26,161	)	$	(40,805	)
Foreign		8,208			(4,940	)		(93	)
Total	$	(25,060	)	$	(31,101	)	$	(40,898	)

Schedule of Components of Provision for Income Taxes

The components of the provision for income taxes were as follows (in thousands):

	Years Ended December 31,
		2017		2016		2015
Current:
Federal	$	—	$	—	$	—
State		2		7		21
Foreign		559		445		88
Total		561		452		109
Deferred:
Federal		—		—		—
State		—		—		—
Foreign		—		—		—
Total		—		—		—
Provision for income taxes	$	561	$	452	$	109

Schedule of Income Taxes Computed at Federal Statutory and Provision Income Taxes

The items accounting for the difference between income taxes computed at the federal statutory income tax rate of 34% and the provision for income taxes consisted of the following (in thousands):

	Years Ended December 31,
		2017			2016			2015
Income tax benefit at statutory rate	$	(8,520	)	$	(10,574	)	$	(13,832	)
Statutory rate change		30,019			—			—
State taxes, net of federal benefit		(2,612	)		(213	)		14
Impact of foreign income taxes		(2,233	)		2,124			119
Stock-based compensation		(7,542	)		2,340			1,629
Foreign exchange loss (gain)		1,990			(1,920	)		—
Change in valuation allowance		(8,782	)		9,510			12,673
Impact of ASU 2016-09		(1,809	)		—			—
Transition tax		695			—			—
Research and development credits		(833	)		(764	)		(674	)
Other		188			(51	)		180
	$	561		$	452		$	109

Schedule of Components of Net Deferred Tax Assets

The Company’snet deferredtaxassets consisted ofthe followingatDecember 31, 2017 and 2016 (in thousands):

	December 31,
Deferred tax assets (liabilities)		2017			2016
Deferred tax assets:
Net operating loss carryforwards	$	49,996		$	58,457
Deferred revenue		604			372
Tax credits		3,662			2,829
Accrued payroll		646			935
Accrued expenses not currently deductible		1,239			2,121
Non-qualified stock options		2,689			3,164
Depreciation and amortization		350			128
Other		84			46
Gross deferred assets		59,270			68,052
Valuation allowance		(59,270	)		(68,052	)
Total deferred tax assets, net of valuation allowance		—			—
Deferred tax liabilities:
Depreciation and amortization		—			—
Unrealized foreign currency gain/loss		—			—
Total deferred tax liabilities		—			—
Net deferred assets	$	—		$	—

Net Change in Total Valuation Allowance

The net changein the total valuationallowancewas as follows (in thousands):

	December 31,
	2017			2016			2015
Balance at beginning of period	$	(68,052	)	$	(58,542	)	$	(45,011	)
Tax valuation increase		(1,324	)		(9,779	)		(14,375	)
Tax valuation decrease		10,106			269			844
Balance at end of period	$	(59,270	)	$	(68,052	)	$	(58,542	)

Summary of Unrecognized Gross Tax Benefits

The total balanceofunrecognizedgross taxbenefits was as follows (in thousands):

	Years Ended December 31,
		2017		2016		2015
Unrecognized tax benefits at beginning of year	$	2,829	$	2,065	$	1,391
Additions for tax positions in prior years		—		—		—
Additions for tax positions in the current year		833		764		674
Unrecognized tax benefits at end of year	$	3,662	$	2,829	$	2,065