Income Taxes (Schedule Of Deferred Tax Assets And Valuation Allowance) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Net operating loss carryforwards	$ 22,300	$ 17,100
Stock-related compensation	9,100	10,600
Research & development credit carryforwards	6,200	6,000
Other	200	500
Total deferred tax assets	37,800	34,200
Valuation allowance	(37,800)	(34,200)
Net deferred tax assets

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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