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Regulatory Matters (Rate Case Action) (Details) - USD ($) $ in Millions | Apr. 24, 2020 | Oct. 31, 2018
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NIPSCO - Electric |  |
Rate Case Action [Line Items] |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  | $ 21.4
Public Utilities, Approved Rate Increase (Decrease), Amount |  | $ (53.5)
Subsequent Event | Columbia Of Pennsylvania [Member] |  |
Rate Case Action [Line Items] |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | $ 100.4 |

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- Definition Amount of public utility's approved rate increase (decrease) by regulatory agency. + References No definition available. + Details
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