Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of components of the income tax provision

The components of the Company’s income tax provision (benefit) are as follows (in thousands):

	Year Ended December 31,
	2017			2016		2015
Current:
Federal	$	—		$	—	$	—
State	18			74		25
Total current provision	18			74		25
Deferred:
Federal	410			547		547
State	40			34		34
Tax Act impact	(2,632		)	—		—
Total deferred (benefit) provision	(2,182		)	581		581
Total income tax (benefit) provision	$	(2,164	)	$	655	$	606

Schedule of overall effective income tax rate

The overall effective income tax rate differs from the statutory federal rate of 34% as follows:

	Year Ended December 31,
	2017		2016		2015
Income tax benefit based on the federal statutory rate	34.0	%	34.0	%	34.0	%
State income taxes, net of federal benefit	9.4		3.2		2.4
Nondeductible expenses	(1.2	)	(1.7	)	(0.3	)
Change in valuation allowance, excluding Tax Act impact	(130.0	)	(33.0	)	(30.7	)
Stock-based compensation	86.5		(4.1	)	(6.4	)
Tax Act impact	7.5		—		—
Other	—		—		0.1
Overall effective income tax rate	6.2	%	(1.6	)%	(0.9	)%

Schedule of components of deferred tax assets (liabilities)

The components of deferred tax assets (liabilities) are as follows (in thousands):

	December 31,
	2017			2016
Deferred income tax assets:
Net operating loss carryforwards	$	99,551		$	95,342
Stock-based compensation	11,854			25,278
Accrued expenses	1,878			3,338
Research and development tax credits	568			543
Other	271			371
Gross deferred tax assets	114,122			124,872
Valuation allowance	(107,046		)	(115,689		)
Net deferred tax assets	7,076			9,183
Deferred tax liabilities:
Property, equipment and software	(3,540		)	(5,424		)
Intangible assets and goodwill	(4,348		)	(6,753		)
Gross deferred tax liabilities	(7,888		)	(12,177		)
Total net deferred tax liabilities	$	(812	)	$	(2,994	)

Schedule of change in the valuation allowance

The change in the valuation allowance for the years ended December 31, 2017, 2016, and 2015 is as follows (in thousands):

	Year Ended December 31,
	2017			2016		2015
Valuation allowance, at beginning of year	$	115,689		$	84,167	$	64,449
Increase in valuation allowance- share-based compensation guidance impact	—			17,959		—
Valuation allowance, at beginning of year, as adjusted	$	115,689		$	102,126	$	64,449
Increase in valuation allowance, excluding Tax Act impact	45,512			13,563		19,718
Decrease in valuation allowance - federal tax rate change	(52,757		)	—		—
Release of valuation allowance due to the Tax Act	(1,398		)	—		—
Valuation allowance, at end of year	$	107,046		$	115,689	$	84,167

Schedule of reconciliation of the total amounts of unrecognized tax benefits

The following is a reconciliation of the total amounts of unrecognized tax benefits (in thousands):

	Year Ended December 31,
	2017			2016		2015
Unrecognized tax benefit, beginning of year	$	3		$	3	$	46
Additions based on current year tax positions				—		—
Additions for prior years’ tax positions	1			—		—
Settlements with tax authorities	(7		)	—		(13		)
Reductions for prior years’ tax positions				—		(30		)
Unrecognized tax benefit, end of year	$	(3	)	$	3	$	3