Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Summary of Income Tax Expense

The following table presents the detail of income tax benefit (expense) for the periods presented (in thousands):

	Year Ended December 31,
	2017			2016			2015
Current:
U.S. - Federal	$	—		$	—		$	—
U.S. - State		(8	)		(15	)		(56	)
Foreign		(126	)		(63	)		(22	)
		(134	)		(78	)		(78	)
Deferred:
U.S. - Federal		241			(91	)		(88	)
U.S. - State		(10	)		1			—
Foreign					—			—
		231			(90	)		(88	)
Total income tax benefit (expense)	$	97		$	(168	)	$	(166	)

Reconciliation of U.S. Federal Statutory Income Tax Rate to Effective Income Tax Rate

The following table presents a reconciliation of the federal statutory rate and our effective tax rate for the periods presented:

	Year Ended December 31,
	2017			2016			2015
U.S. Statutory Rate		34.0	%		34.0	%		34.0	%
Change in valuation allowance		56.4			(11.8	)		9.9
State taxes (net of federal benefit)		1.9			(4.4	)		3.8
Federal research and development credit		7.1			67.4			(60.8	)
Incentive stock options		12.5			(46.2	)		19.5
Unrecognized tax benefits		(3.5	)		(47.1	)		28.8
Preferred stock warrant revaluation		—			12.6			(22.4	)
Impact of Tax Cuts and Jobs Act of 2017		(113.5	)		—			—
Return to provision - deductible transaction costs		5.6			—			—
Other, net		0.1			(15.5	)		2.9
Effective income tax rate		0.6	%		(11.0	)%		15.7	%

Summary of Significant Components Deferred Tax Assets and Liabilities

Deferred federal, state and foreign income taxes reflect the net tax impact of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and such amounts for tax purposes. The following table presents the significant components of our deferred tax assets and liabilities as of the dates presented (in thousands):

	December 31,
	2017			2016
Net operating loss carryforwards (1)	$	27,090		$	34,287
Credit carryforwards		7,478			6,492
Capitalized research and development		3,665			6,992
Deferred rent		1,189			1,825
Allowances		1,466			767
Deferred compensation		218			1,209
Deferred revenue		108			331
Stock compensation		525			220
Deferred tax assets		41,739			52,123
Less: valuation allowance		(41,130	)		(50,959	)
Net deferred tax assets	$	609		$	1,164
Deferred tax liability
Goodwill		(532	)		(766	)
Depreciation and amortization		(609	)		(1,164	)
Deferred tax liabilities		(1,141	)		(1,930	)
Net deferred tax liability	$	(532	)	$	(766	)
(1)   During the prior year, we recorded an increase to the NOL and increase to the valuation allowance of $727,000 as a result of the adoption of ASU 2016-09, “Improvements to Employee Share-Based Payment Accounting.”

Total Balance of Unrecognized Tax Benefits

The following table presents the total balance of unrecognized tax benefits as of the dates presented (in thousands):

	Year ended December 31,
	2017		2016		2015
Unrecognized tax benefits at beginning of the period	$	2,597	$	1,878	$	1,732
Gross increases to tax positions in prior periods		2		210		—
Gross increases to tax positions in current periods		307		509		146
Unrecognized tax benefits at end of the period	$	2,906	$	2,597	$	1,878