Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Reconciliation of Expected Income Tax Benefit

A reconciliation of the expected income tax benefit computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows for the years ended December 31, 2016, 2015 and 2014:

	Years Ended December 31,
	2016		2015		2014
Income tax computed at federal statutory tax rate	34.0%		34.0%		34.0%
State taxes, net of federal benefit	5.2%		5.3%		5.3%
Research and development credits	1.4%		2.0%		2.6%
Other permanent differences	6.1%		(2.0)%		(0.8)%
Foreign rate differential	(0.1)%		(0.1)%		—
Foreign withholding taxes	(0.4)%		—		—
SEC settlement liability	—		(9.1)%		—
Other	(6.6)%		(3.8)%		(5.7)%
Change in valuation allowance	(39.6)%		(26.3)%		(35.4)%
Total		—		—		—

Company Net Deferred Tax Assets

The Company’s net deferred tax assets as of December 31, 2016 and 2015 are as follows (in thousands):

	2016		2015
NOL carryforwards	$	182,433	$	170,200
Research and development credits		13,060		12,721
Deferred revenue		867		1,451
Other temporary differences		4,570		5,935
Valuation allowance	(200,930)		(190,307)
Total	$	—	$	—

Reconciliation of Gross Uncertain Tax Positions

The following is a reconciliation of the Company’s gross uncertain tax positions at December 31, 2016, 2015 and 2014:

	Years Ended December 31,
	2016		2015		2014
	(in thousands)
Amount established upon adoption	$	1,200	$	1,200	$	1,200
Additions for current year tax provisions		—		—		—
Additions for prior year tax provisions		—		—		—
Reductions of prior year tax provisions		—		—		—
Balance as of end of year	$	1,200	$	1,200	$	1,200