Income Taxes, Tax Credit Carryforwards (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Federal [Member]
Operating Loss Carryforwards [Abstract]
Net operating loss carryforwards	$ 242.8
California [Member]
Operating Loss Carryforwards [Abstract]
Net operating loss carryforwards	398.8
Research and Development [Member] | Federal [Member]
Tax Credit Carryforwards [Abstract]
Tax credit carryforwards	169.7
Research and Development [Member] | California [Member]
Tax Credit Carryforwards [Abstract]
Tax credit carryforwards	124.4
State [Member]
Operating Loss Carryforwards [Abstract]
Operating loss carryforwards utilized	$ 3.2