Income Taxes (Summary Of Tax Loss And Tax Credit Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Tax Credit Carryforward [Line Items]
Deferred tax asset on tax carryforwards	$ 120.7	$ 124.8
Valuation Allowance, Amount	(150.0)	$ (124.3)
Tax Loss and Credit Carryforwards [Member]
Tax Credit Carryforward [Line Items]
Deferred tax asset on tax carryforwards	120.7
Valuation Allowance, Amount	(115.2)
Net deferred tax asset on tax carryforwards	5.5
U.S. Federal Tax Credits [Member]
Tax Credit Carryforward [Line Items]
2020-2024	2.9
After 2024	2.7
Indefinite	0.0
Total tax carryforwards	5.6
Deferred tax asset on tax carryforwards	5.6
Valuation Allowance, Amount	(5.5)
Net deferred tax asset on tax carryforwards	0.1
U.S Federal Tax Losses [Member]
Tax Credit Carryforward [Line Items]
2020-2024	0.0
After 2024	0.8
Indefinite	0.0
Total tax carryforwards	0.8
Deferred tax asset on tax carryforwards	0.2
Valuation Allowance, Amount	(0.2)
Net deferred tax asset on tax carryforwards	0.0
U.S. State Tax Credits [Member]
Tax Credit Carryforward [Line Items]
2020-2024	2.8
After 2024	2.7
Indefinite	22.1
Total tax carryforwards	27.6
Deferred tax asset on tax carryforwards	21.8
Valuation Allowance, Amount	(20.1)
Net deferred tax asset on tax carryforwards	1.7
U.S. State Tax Losses [Member]
Tax Credit Carryforward [Line Items]
2020-2024	71.7
After 2024	810.8
Indefinite	3.6
Total tax carryforwards	886.1
Deferred tax asset on tax carryforwards	45.5
Valuation Allowance, Amount	(43.9)
Net deferred tax asset on tax carryforwards	1.6
Non-U.S. Tax Losses [Member]
Tax Credit Carryforward [Line Items]
2020-2024	34.9
After 2024	4.9
Indefinite	201.3
Total tax carryforwards	241.1
Deferred tax asset on tax carryforwards	47.6
Valuation Allowance, Amount	(45.5)
Net deferred tax asset on tax carryforwards	$ 2.1