Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Taxes

Schedule of components of deferred tax assets

	2017		2016
	(In thousands)
Operating loss carryforwards	$	53,276	$	56,832
Tax credit carryforwards		14,099		9,428
Other		7,552		7,710
Total deferred tax assets		74,927		73,970
Valuation allowance		(74,927)		(73,970)
Net deferred tax assets	$	—	$	—

Schedule of difference between U.S. federal corporate tax rate and Company effective tax rate

	2017		2016		2015
Expected federal income tax rate	(34.0)	%	(34.0)	%	(34.0)	%
Expiring credits and NOLs	—		—		—
Change in valuation allowance	0.9		42.2		39.8
Federal and state credits	(6.9)		(9.9)		(7.4)
State income taxes, net of federal benefit	(3.7)		(3.7)		(4.5)
Permanent differences	2.4		3.5		2.4
Rate change related to TCJA	41.9		—		—
Other	(0.6)		1.9		3.7
Effective tax rate	0.0	%	0.0	%	0.0	%