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Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions |  | 12 Months Ended |
--- | --- | --- | ---
Oct. 31, 2022 | Dec. 31, 2022 | Dec. 31, 2021
Regulatory Assets and Liabilities Disclosure [Line Items] |  |  |
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided |  | $ 1,324.7 | $ 1,207.0
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided |  | 50 years |
Columbia of Maryland COVID Relief Funds |  | $ 0.8 |
COVID-19 related regulatory asset |  | 2,580.8 | 2,492.2
Regulatory Liabilities |  | 2,012.6 | 1,980.0
Overrecovered Gas And Fuel Costs |  |  |
Regulatory Assets and Liabilities Disclosure [Line Items] |  |  |
Regulatory Liabilities |  | 20.6 | $ 5.4
Columbia Of Ohio |  |  |
Regulatory Assets and Liabilities Disclosure [Line Items] |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | $ 68.2 | $ 221.4 |
Public Utilities, Requested Rate Increase (Decrease), Percentage | 7.97% | 21.30% |
NIPSCO - Electric | Overrecovered Gas And Fuel Costs |  |  |
Regulatory Assets and Liabilities Disclosure [Line Items] |  |  |
Regulatory Liabilities |  | $ 8.0 |

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- Definition Amount of public utility's requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
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- Definition The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
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- Definition Remaining balance of regulatory assets for which no return on investment during recovery is provided. In some cases, a regulator may permit an enterprise to include a cost that would be charged to expense by an unregulated enterprise as an allowable cost over a period of time by amortizing that cost for rate-making purposes, but the regulator does not include the unrecovered amount in the rate base. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 55 -Paragraph 2 -URI https://asc.fasb.org/extlink&oid=123406419&loc=d3e44360-110383 + Details
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