Commitments And Contingencies (Narrative) (Details) $ / shares in Units, $ in Millions		1 Months Ended				12 Months Ended
	May 13, 2021 USD ($)	Jun. 30, 2021 USD ($) $ / shares	May 31, 2020 USD ($)	Nov. 30, 2019 USD ($)	Jan. 31, 2019 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 11, 2021 USD ($)	May 31, 2019 ft²	Jan. 31, 2017 ft²
Commitments and Contingencies [Line Items]
Director and officer insurance premium payable	$ 2.6
Insurance down payment	0.7
Financed insurance policy balance	$ 1.9
Financed insurance policy interest rate	3.69%
Lease term											5 years
Area Of Lease | ft²											15,700
Rent expense, including common area maintenance charges						$ 1.9	$ 1.7	$ 0.5
Robert W. Duggan [Member] | Private Placement [Member]
Commitments and Contingencies [Line Items]
Principal sum		$ 41.0
Accrued interest		$ 0.6
Price per share | $ / shares		$ 16.40
Lease Amendment - Phase One [Member]
Commitments and Contingencies [Line Items]
Area Of Lease | ft²										13,300
Lease Amendment - Phase Two [Member]
Commitments and Contingencies [Line Items]
Area Of Lease | ft²										21,300
Accounting Standards Update 2016-02 [Member]
Commitments and Contingencies [Line Items]
Increase in right-of-use assets			$ 4.8	$ 3.0	$ 2.0	8.8
Increase in lease liability						10.8
Loan Agreement [Member] | Robert W. Duggan [Member]
Commitments and Contingencies [Line Items]
Principal sum									$ 41.0
Debt instrument, stated interest rate									5.00%
Interest expense						$ 0.6