Organization (Details)	Mar. 31, 2026 numberOfSubsidiary state MW
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of states in which entity operates \| state	9
Number of wholly owned for-profit subsidiaries \| numberOfSubsidiary	3
Number of wholly owned not-for-profit subsidiaries \| numberOfSubsidiary	1
Jointly Owned Electricity Generation Plant \| Missouri Basin Power Project (MBPP)
Schedule of Equity Method Investments [Line Items]
Proportionate ownership share	42.27%
Jointly Owned Electricity Generation Plant \| Laramie River Station
Schedule of Equity Method Investments [Line Items]
Generating capacity \| MW	1,700
Nemadji River Generation (NRG) \| Jointly Owned Electricity Generation Plant \| Nemadji Trail Energy Center (NTEC)
Schedule of Equity Method Investments [Line Items]
Proportionate ownership share	30.00%
Generating capacity \| MW	600

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The proportionate share of interest (percent) in a jointly owned utility plant.

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The number of states the entity operates in as of the balance sheet date.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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