Business Combinations, Asset Acquisitions, Transaction between Entities under Common Control, and Joint Venture Formation (Details) $ in Millions	6 Months Ended
Jun. 30, 2025 USD ($) customers	Dec. 31, 2024 customers
Asset Acquisition [Line Items]
Number of customers		842,100
Energy West
Asset Acquisition [Line Items]
Asset Acquisition, Price of Acquisition, Expected \| $	$ 36.5
Northwestern Energy Group Inc.
Asset Acquisition [Line Items]
Number of customers	33,000

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482573/350-20-50-4

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 805
-SubTopic 50
-Name Accounting Standards Codification
-Section 15
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480123/805-50-15-3

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