Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of loss before income taxes, domestic and foreign

Our loss before provision for income taxes was as follows (in thousands):

	Years Ended December 31,
	2017			2016			2015
United States	$	(22,994	)	$	(8,174	)	$	(7,641	)
Foreign	79			(424		)	(278		)
Loss before provision for income taxes	$	(22,915	)	$	(8,598	)	$	(7,919	)

Components of provision for income taxes

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

	Years Ended December 31,
	2017		2016			2015
Current provision (benefit):
Federal	$	—	$	—		$	—
State	5		5			5
Foreign	64		(14		)	(13		)
Total current provision (benefit)	69		(9		)	(8		)
Deferred provision (benefit):
Federal	—		—			(293		)
State	—		—			(21		)
Foreign	12		(31		)	(16		)
Total deferred provision (benefit)	12		(31		)	(330		)
Provision for (benefit from) income taxes	$	81	$	(40	)	$	(338	)

Reconciliation of provision for income taxes calculated at the statutory rate to provision for income taxes

Reconciliation of the provision for income taxes calculated at the statutory rate to our provision for (benefit from) income taxes is as follows (in thousands):

	Years Ended December 31,
	2017			2016			2015
Tax benefit at federal statutory rate	$	(7,791	)	$	(2,924	)	$	(2,693	)
State taxes	48			127			1,126
Research and development credits	(399		)	(161		)	(85		)
Foreign operations taxed at different rates	(2		)	30			31
Stock-based compensation	(216		)	327			77
Other nondeductible items	399			660			(43		)
Change in valuation allowance	(26,058		)	1,901			1,249
Change in statutory tax rate	34,100			—			—
Provision for (benefit from) income taxes	$	81		$	(40	)	$	(338	)

Significant components of our deferred tax assets and liabilities

Significant components of our deferred tax assets and liabilities are as follows (in thousands):

	December 31,
	2017			2016
Deferred tax assets:
Net operating losses	$	53,901		$	72,588
Credits	6,221			5,016
Deferred revenues	3,334			1,025
Stock-based compensation	2,872			3,750
Reserves and accruals	2,028			2,952
Depreciation	1,573			2,516
Intangible assets	3,172			5,536
Capital losses	576			933
Unrealized gain/loss	295			277
Other assets	78			110
Total deferred tax assets:	74,050			94,703
Deferred tax liabilities:
Other	(115		)	(103		)
Total deferred tax liabilities:	(115		)	(103		)
Valuation allowance	(74,010		)	(94,663		)
Net deferred tax liabilities	$	(75	)	$	(63	)

Summary of federal, state and foreign NOL carryforwards and federal research and development tax credits

The following table sets forth our federal, state and foreign NOL carryforwards and federal research and development tax credits as of December 31, 2017 (in thousands):

	December 31, 2017
	Amount		Expiration Years
Net operating losses, federal	$	224,536	2022-2037
Net operating losses, state	110,802		2017-2037
Tax credits, federal	6,433		2022-2037
Tax credits, state	7,970		Do not expire
Net operating losses, foreign	382		Various

Reconciliation of the beginning and ending amount of unrecognized tax benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands):

	Rollforward Table (at Gross): As of
	December 31,
	2017			2016			2015
Balance at beginning of year	$	8,566		$	8,152		$	7,838
Additions based on tax positions related to current year	880			459			368
Reductions to tax provision of prior years	(24		)	(45		)	(54		)
Balance at end of year	$	9,422		$	8,566		$	8,152