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Nature of Operations And Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 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	3.30%	2.60%	3.00%
Inventory valued using LIFO	$ 44.9	$ 42.3
Excess of replacement over LIFO value	(13.6)	(19.6)
Inventory valued using the weighted average cost methodology	$ 282.4	$ 148.8

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Basis Of Accounting Presentation [Line Items]

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Number of customers

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Pre tax rate for allowance for funds used during construction

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The excess of replacement or current cost over the stated LIFO (last in first out) inventory value when the LIFO inventory method is utilized.

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-Publisher FASB
-Name Accounting Standards Codification
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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.

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-Topic 320
-SubTopic 10
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The amount of LIFO (last in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.

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The amount of weighted average cost inventory present at the reporting date when inventory is valued using different valuation methods.

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