Income Taxes Components of deferred tax asset/ liability (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Net operating loss carry forwards	$ 100,378	$ 83,522
Tax credit carry forwards	19,248	18,940
Fixed and intangible assets	597	868
Capitalized research and development costs	58	58
Stock based compensation and other reserves and allowances	3,445	3,828
Gross deferred income tax assets	123,726	107,216
Valuation allowance	(123,726)	(107,216)
Net deferred income tax assets	$ 0	$ 0
Percentage of deferred tax assets on which valuation allowance is created		100.00%