Income Taxes (Summary Of Tax Loss And Tax Credit Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Tax Credit Carryforward [Line Items]
Deferred tax asset on tax carryforwards	$ 97.7	$ 111.2
Valuation allowance on tax carryforwards	(99.7)	$ (141.5)
Total
Tax Credit Carryforward [Line Items]
Deferred tax asset on tax carryforwards	97.8
Valuation allowance on tax carryforwards	(91.4)
Net deferred tax asset on tax carryforwards	6.4
U.S. Federal Tax Credits
Tax Credit Carryforward [Line Items]
2023-2027	0.0
After 2027	4.8
Indefinite	0.0
Total tax carryforwards	4.8
Deferred tax asset on tax carryforwards	4.8
Valuation allowance on tax carryforwards	(4.8)
Net deferred tax asset on tax carryforwards	0.0
U.S. Federal Tax Losses
Tax Credit Carryforward [Line Items]
2023-2027	0.0
After 2027	0.7
Indefinite	0.0
Total tax carryforwards	0.7
Deferred tax asset on tax carryforwards	0.1
Valuation allowance on tax carryforwards	(0.1)
Net deferred tax asset on tax carryforwards	0.0
U.S. State Tax Credits
Tax Credit Carryforward [Line Items]
2023-2027	2.7
After 2027	0.9
Indefinite	20.8
Total tax carryforwards	24.4
Deferred tax asset on tax carryforwards	19.3
Valuation allowance on tax carryforwards	(19.0)
Net deferred tax asset on tax carryforwards	0.3
U.S. State Tax Losses
Tax Credit Carryforward [Line Items]
2023-2027	111.2
After 2027	760.7
Indefinite	10.5
Total tax carryforwards	882.4
Deferred tax asset on tax carryforwards	44.2
Valuation allowance on tax carryforwards	(42.8)
Net deferred tax asset on tax carryforwards	1.4
Non- U.S. Tax Losses
Tax Credit Carryforward [Line Items]
2023-2027	4.2
After 2027	3.7
Indefinite	117.5
Total tax carryforwards	125.4
Deferred tax asset on tax carryforwards	29.4
Valuation allowance on tax carryforwards	(24.7)
Net deferred tax asset on tax carryforwards	$ 4.7