Segments Of Business (Narrative) (Details) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2019 USD ($)
Goodwill [Line Items]
Number of Reportable Segments	2
Number of counties in which electric service provided by Electric Operations	20
Columbia Of Massachusetts
Goodwill [Line Items]
Goodwill, Impairment Loss		$ 204.8

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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