The net result for the period of deducting operating expenses from operating revenues.

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Name:	us-gaap_OperatingIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Income Taxes - Tax Credit Carryover (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Tax credit carryovers
Gross net operating loss	$ 26,647	$ 28,948
Federal
Tax credit carryovers
Reduction In Credit carryforwards			$ 1,400
California
Tax credit carryovers
Reduction In Credit carryforwards			$ 697
Research \| Federal
Tax credit carryovers
Tax credit carryovers	0
Research \| California
Tax credit carryovers
Tax credit carryovers	$ 382