Accumulated Other Comprehensive Loss (Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (35.8)	$ (123.6)	$ (126.8)	$ (156.7)
Other Comprehensive Income (Loss) before reclassifications	11.6	5.9	101.4	38.0
Amounts reclassified from accumulated other comprehensive income (loss)	0.7	0.3	1.9	1.3
Net current-period other comprehensive income (loss)	12.3	6.2	103.3	39.3
Ending Balance	(23.5)	(117.4)	(23.5)	(117.4)
Interest Rate Risk
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net current-period other comprehensive income (loss)			119.2
Gains and Losses on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(7.5)	4.4	2.1	6.0
Other Comprehensive Income (Loss) before reclassifications	(4.6)	(0.6)	(14.4)	(2.0)
Amounts reclassified from accumulated other comprehensive income (loss)	0.1	(0.2)	0.3	(0.4)
Net current-period other comprehensive income (loss)	(4.5)	(0.8)	(14.1)	(2.4)
Ending Balance	(12.0)	3.6	(12.0)	3.6
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(19.5)	(113.1)	(122.5)	(147.9)
Other Comprehensive Income (Loss) before reclassifications	16.2	6.5	119.1	41.3
Amounts reclassified from accumulated other comprehensive income (loss)	0.0	0.1	0.1	0.1
Net current-period other comprehensive income (loss)	16.2	6.6		41.4
Ending Balance	(3.3)	(106.5)	(3.3)	(106.5)
Pension and OPEB Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(8.8)	(14.9)	(6.4)	(14.8)
Other Comprehensive Income (Loss) before reclassifications	0.0	0.0	(3.3)	(1.3)
Amounts reclassified from accumulated other comprehensive income (loss)	0.6	0.4	1.5	1.6
Net current-period other comprehensive income (loss)	0.6	0.4	(1.8)	0.3
Ending Balance	$ (8.2)	$ (14.5)	$ (8.2)	$ (14.5)

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details