Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

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,
	2018			2017			2016
Current:
U.S. - Federal	$	—		$	—		$	—
U.S. - State		(23	)		(8	)		(15	)
Foreign		(140	)		(126	)		(63	)
		(163	)		(134	)		(78	)
Deferred:
U.S. - Federal		404			241			(91	)
U.S. - State		(8	)		(10	)		1
Foreign		—			—			—
		396			231			(90	)
Total income tax benefit (expense)	$	233		$	97		$	(168	)

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,
	2018			2017			2016
U.S. Statutory Rate		21.0	%		34.0	%		34.0	%
Change in valuation allowance		(20.6	)		56.4			(11.8	)
State taxes (net of federal benefit)		0.5			1.9			(4.4	)
Federal research and development credit		4.1			7.1			67.4
Incentive stock options		(2.9	)		12.5			(46.2	)
Unrecognized tax benefits		(1.0	)		(3.5	)		(47.1	)
Preferred stock warrant revaluation		—			—			12.6
Impact of Tax Cuts and Jobs Act of 2017		—			(113.5	)		—
Return to provision - deductible transaction costs		—			5.6			—
Other, net		(0.4	)		0.1			(15.5	)
Effective income tax rate		0.7	%		0.6	%		(11.0	%)

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, 2018			December 31, 2017
Net operating loss carryforwards	$	34,279		$	27,090
Credit carryforwards		8,071			7,478
Capitalized research and development		2,969			3,665
Deferred rent		1,021			1,189
Allowances		1,309			1,466
Deferred compensation		230			218
Deferred revenue		40			108
Stock-based compensation		1,340			525
Other		108			—
Deferred tax assets		49,367			41,739
Less: Valuation allowance		(48,481	)		(41,130	)
Net deferred tax assets		886			609
Deferred tax liability:
Goodwill		(590	)		(532	)
Depreciation and amortization		(433	)		(609	)
Deferred tax liabilities		(1,023	)		(1,141	)
Net deferred tax liability	$	(137	)	$	(532	)

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,
	2018		2017		2016
Balance at beginning of period	$	2,906	$	2,597	$	1,878
Gross increase to tax positions in prior periods		—		2		210
Gross increase to tax positions in current periods		253		307		509
Balance at end of period	$	3,159	$	2,906	$	2,597