Subsequent Events	12 Months Ended
Dec. 31, 2025
Subsequent Events [Abstract]
Subsequent Events	(18) SUBSEQUENT EVENTS Except as described below, there have been no events subsequent to December 31, 2025, which would require recognition in the Consolidated Financial Statements or disclosures. See Note 8, for information regarding the repayment of our $300 million, 3.95% senior unsecured notes on their January 15, 2026, maturity date. See Notes 3 and 15, for information regarding the January 2026 transfer of renewable energy credits. See Note 17, for recent updates regarding the pending merger with NorthWestern.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/855/tableOfContent

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 855
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483399/855-10-50-2

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