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Nature of Operations And Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
Basis Of Accounting Presentation [Line Items] |  |  |
Number of customers | 3,700,000 |  |
Other than Temporary Impairment Losses, Investments | $ 0.0 | $ 0.0 | $ 0.0
Pre-tax rate for allowance for funds used during construction | 3.40% | 3.30% | 2.60%
Inventory valued using LIFO | $ 43.0 | $ 44.9 |
Excess of replacement over LIFO value | 7.7 | 13.6 |
Inventory valued using the weighted average cost methodology | $ 488.7 | $ 282.4 |

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- Definition The excess of replacement or current cost over the stated LIFO (last in first out) inventory value when the LIFO inventory method is utilized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(6)(c)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 8A -URI https://asc.fasb.org/extlink&oid=124260329&loc=SL6284422-111562 + Details
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