Income Taxes (Summary Of Tax Loss And Tax Credit Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Tax Credit Carryforward [Line Items]
Deferred tax asset on tax carryforwards	$ 111.2	$ 124.5
Valuation allowance on tax carryforwards	(141.5)	$ (153.4)
Total
Tax Credit Carryforward [Line Items]
Deferred tax asset on tax carryforwards	111.2
Valuation allowance on tax carryforwards	(106.4)
Net deferred tax asset on tax carryforwards	4.8
U.S. Federal Tax Credits
Tax Credit Carryforward [Line Items]
2022-2026	0.0
After 2026	3.8
Indefinite	0.0
Total tax carryforwards	3.8
Deferred tax asset on tax carryforwards	3.8
Valuation allowance on tax carryforwards	(3.8)
Net deferred tax asset on tax carryforwards	0.0
U.S. Federal Tax Losses
Tax Credit Carryforward [Line Items]
2022-2026	0.0
After 2026	0.7
Indefinite	0.0
Total tax carryforwards	0.7
Deferred tax asset on tax carryforwards	0.2
Valuation allowance on tax carryforwards	(0.2)
Net deferred tax asset on tax carryforwards	0.0
U.S. State Tax Credits
Tax Credit Carryforward [Line Items]
2022-2026	2.7
After 2026	1.7
Indefinite	22.0
Total tax carryforwards	26.4
Deferred tax asset on tax carryforwards	21.1
Valuation allowance on tax carryforwards	(20.3)
Net deferred tax asset on tax carryforwards	0.8
U.S. State Tax Losses
Tax Credit Carryforward [Line Items]
2022-2026	114.3
After 2026	764.2
Indefinite	9.5
Total tax carryforwards	888.0
Deferred tax asset on tax carryforwards	43.9
Valuation allowance on tax carryforwards	(42.2)
Net deferred tax asset on tax carryforwards	1.7
Non- U.S. Tax Losses
Tax Credit Carryforward [Line Items]
2022-2026	5.3
After 2026	5.8
Indefinite	184.8
Total tax carryforwards	195.9
Deferred tax asset on tax carryforwards	42.2
Valuation allowance on tax carryforwards	(39.9)
Net deferred tax asset on tax carryforwards	$ 2.3