Borrowings and Other Financing Instruments - Long-Term Borrowings (Details) - Series Due June 1, 2052 - Bonds [Member]	Sep. 30, 2022 USD ($)
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 200,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.15%

Face (par) amount of debt instrument at time of issuance.

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Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant