Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of Provision for Federal Income Taxes

  The provision for federal income taxes in 2016, 2015, and 2014 is as follows:

	December 31,
	2016		2015		2014
Current
Federal	$	247	$	—	$	—
State		—		—		—
		247		—		—
Deferred
Federal	$	—	$	—	$	—
State		—		—		—
Total deferred tax expense		—		—		—
Total income tax expense	$	247	$	—	$	—

Schedule of Income (Loss) Before Income Taxes Attributed to Geographic Locations

	December 31,
	2016			2015			2014
United States	$	(10,421	)	$	(17,671	)	$	(49,850	)
Foreign		(85,149	)		(64,506	)		(7,663	)
Net loss before provision for income taxes	$	(95,570	)	$	(82,177	)	$	(57,513	)

Summary of Statutory Federal Tax Rate to Income or Loss before Taxes

Income tax expense in 2016, 2015, and 2014 differed from the amount expected by applying the statutory federal tax rate to the income or loss before taxes as summarized below:

	December 31,
	2016			2015			2014
Federal tax benefit at statutory rate		34	%		34	%		34	%
State tax benefit net of federal effect		—			—			—
Change in valuation allowance		(3	)%		(8	)%		(23	)%
Research and development credits		4	%		2	%		2	%
Non-deductible warrant		—			—			(7	)%
Foreign loss not benefitted		(30	)%		(27	)%		(5	)%
Other Non-deductible expenses		(5	)%		(2	)%		(1	)%
Total		0	%		0	%		0	%

Significant Components of Net Deferred Tax Assets

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

	December 31,
	2016			2015
Net operating loss carry forwards	$	32,500		$	33,684
Research and development tax credits		8,142			4,982
Stock based compensation and other		7,256			4,465
Depreciation and amortization		78			42
Total deferred tax assets		47,976			43,173
Less: Valuation allowance		(47,976	)		(43,173	)
Net deferred tax assets	$	—		$	—

Reconciliation of Amount of Unrecognized Tax Benefits

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

	Amount
Balance at January 1, 2014	$	287
Decreases based on tax positions taken during a prior period		(102	)
Increases based on tax positions taken during a current period		147
Balance at December 31, 2014	$	332
Increases based on tax positions taken during a prior period		3,562
Increases based on tax positions taken during a current period		167
Balance at December 31, 2015	$	4,061
Gross increase related to prior year tax positions		4,628
Gross decrease related to prior year tax positions		(3,559	)
Gross increase related to current year positions		4,986
Reductions to unrecognized tax benefits related to lapsing statute of limitations		-
Balance at December 31, 2016	$	10,116