Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Taxes [Abstract]

Total provision for income taxes

The total income tax benefit consists of the following (in thousands):

	Year ended December 31,
	2014		2013			2012
Federal income tax (benefit) provision	$	-	$	(14	)	$	(74	)
Total	$	-	$	(14	)	$	(74	)

Reconciliation between the tax provision computed at the federal statutory income tax rate and actual effective income tax rate

Reconciliation between the tax provision computed at the federal statutory income tax rate of 34% and the Company’s actual effective income tax rate is as follows:

	Year ended December 31,
	2014			2013			2012
Federal tax at statutory rate		34	%		34	%		34	%
Warrant valuation		40	%		-17	%		-4	%
Permanent items and other		-1	%		0	%		-1	%
Valuation allowance		-73	%		-17	%		-29	%
Total		0	%		0	%		0	%

Components of net deferred tax assets

The significant components of net deferred tax assets as of December 31, 2014 and 2013 were as follows (in millions):

	December 31,
	2014			2013
Capitalized research and development expenses	$	50.9		$	49.4
Net operating loss carryforwards		105.0			78.4
Research and development and other credit carryforwards		12.1			8.8
Other		22.1			23.5
Total deferred tax assets		190.1			160.1
Valuation allowance		(190.1	)		(160.1	)
Net deferred tax assets	$	-		$	-

Schedule of unrecognized tax benefits

The following table summarizes the Company's activity related to its unrecognized tax benefits (in thousands):

	2014		2013		2012
Balance at January 1	$	4,274	$	4,104	$	-
Increase related to current year tax position		720		164		49
Increase related to prior year tax position		509		6		4,055
Balance at December 31	$	5,503	$	4,274	$	4,104