Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Taxes

Schedule of significant components of the Company's deferred tax assets

	As of December 31,
(In thousands)	2015			2014
Deferred tax assets:
Net operating loss carryforwards	$	392,000		$	386,000
Deferred revenues		1,000			2,000
Research and development tax credit carryforwards		53,000			53,000
Other		17,000			18,000
Total deferred tax assets		463,000			459,000
Valuation allowance		(463,000	)		(459,000	)
Net deferred tax assets	$	—		$	—

Schedule of the differences between the U.S. federal statutory income tax rate to the Company's effective tax rate

        The differences between the U.S. federal statutory income tax rate to our effective tax rate are as follows:

	Year Ended December 31,
	2015			2014			2013
U.S. federal statutory income tax rate		34.00	%		35.00	%		34.00	%
Non-deductible executive compensation		(1.94	)		(0.16	)		(0.07	)
Stock-based compensation		(0.23	)		(1.11	)		0.28
Federal and state research credits		—			12.66			3.63
Effect of Spin-Off Transaction		—			(203.2	)		—
Other		(0.56	)		(4.04	)		(2.51	)
Change in valuation allowance		(31.27	)		160.85			(35.33	)
Effective tax rate		(0.00	)%		(0.00	)%		(0.00	)%

Reconciliation of gross unrecognized tax benefits

        A reconciliation of the beginning and ending balances of the total amounts of unrecognized tax benefits are as follows (in thousands):

Unrecognized tax benefits as of December 31, 2012	$	52,500
Gross decrease for tax positions for prior years		(565	)
Gross increase in tax positions for current year		5,485
Unrecognized tax benefits as of December 31, 2013		57,420
Gross decrease for tax positions for prior years		(42,650	)
Gross increase in tax positions for current year		689
Unrecognized tax benefits as of December 31, 2014		15,459
Gross increase in tax positions for current year		29
Unrecognized tax benefits as of December 31, 2015	$	15,488