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Operations and Significant Accounting Policies - Other Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Other Income
Total Other Income	$ 68.7	$ 2.3	$ 75.3	$ 16.4
Pension and Other Postretirement Benefit Plan Non-Service Credits
Other Income
Total Other Income	1.8	1.9	5.5	7.2
Interest and Investment Income (b)
Other Income
Total Other Income	6.6	(0.4)	8.7	(1.3)
AFUDC - Equity
Other Income
Total Other Income	1.1	0.7	2.5	2.4
PSA Liability
Other Income
Total Other Income	0.0	0.0	0.0	10.2
Arbitration Award
Other Income
Total Other Income	58.4	0.0	58.4	0.0
Other
Other Income
Total Other Income	0.8	$ 0.1	0.2	$ (2.1)
Interest Income Related To Interest Awarded As Part Of An Arbitration Ruling
Other Income
Total Other Income	$ 5.1		$ 5.1

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Amount of income (expense) related to nonoperating activities, classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

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