Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

The provision for income taxes is based on net loss before income taxes as follows:



	DECEMBER 31,
(in thousands)	2017			2016			2015
Net loss before income taxes:
United States	$	(133,113	)	$	(88,123	)	$	(59,211	)
Other	(13,750		)	(10,743		)	(15,013		)
Net loss before income taxes	$	(146,863	)	$	(98,866	)	$	(74,224	)

The components of the provision for income taxes are as follows:
	DECEMBER 31,
(in thousands, except percentages)	2017			2016			2015
Provision for income taxes:
Current:
United States	$	(24	)	$	193		$	139
Other	—			—			—
Total	$	(24	)	$	193		$	139
Deferred:
United States	$	(1,734	)	$	—		$	—
Other	—			—			—
Total	(1,734		)	—			—
Provision for income taxes	$	(1,758	)	$	193		$	139
Effective tax rate	1.20		%	(0.19		)%	(0.19		)%

Significant components of the Company’s net deferred income tax assets as of December 31, 2017 and 2016 consist of the following:



	DECEMBER 31,
(in thousands)	2017			2016
Net deferred tax assets:
Net operating loss carryforwards	$	58,172		$	39,188
Stock-based compensation	13,681			11,845
U.S. tax credit carryforwards	4,182			4,566
Envisia asset acquisition	7,107			—
Other assets, net	242			1,138
Valuation allowance	(83,384		)	(56,737		)
Total net deferred income taxes	$	—		$	—

A reconciliation of the statutory tax rates and the effective tax rates for the years ended December 31, 2017, 2016 and 2015 is as follows:



	DECEMBER 31,
	2017		2016		2015
U.S. federal tax rate	35.00	%	35.00	%	35.00	%
Impact of federal tax legislation	25.82	%	—	%	—	%
State income taxes, net of federal benefit	7.71	%	5.34	%	(0.90	)%
Taxable gain resulting from IP Assignment	—	%	—	%	(75.31	)%
Non-taxable foreign loss	(0.51	)%	(2.69	)%	(6.98	)%
Tax deferral from IP Assignment	(0.10	)%	(0.19	)%	3.56	%
Other	(2.11	)%	(1.45	)%	0.02	%
Change in valuation allowance	(64.61	)%	(36.20	)%	44.42	%
Effective tax rate	1.20	%	(0.19	)%	(0.19	)%