Income Taxes (Provision for Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory rate	$ (24,467)	$ (41,888)
Change in valuation allowance	102,583	55,167
Share-based compensation expense	7,532	4,041
Section 382 limited tax attributes/expired	0	1,936
Establishment of NOL’s and credits (post 382 change)	(81,368)	0
Research and development credits	(2,599)	(5,164)
Foreign rate differential	(62)	(58)
Other permanent differences	(307)	415
Provision for income taxes	$ 0	$ 0

Effective Income Tax Rate Reconciliation, Establishment Of NOLs And Credits

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Income tax reconciliation expired tax attributes.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority noncontrolling interest income (loss), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, increase (decrease) in enacted tax rate, prior year income taxes, increase (decrease) in deferred tax asset valuation allowance, and other adjustments.

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