Regulatory and Rate Matters - TXNM (Details) - USD ($)	Sep. 15, 2026	Sep. 04, 2026	Aug. 10, 2026	Jul. 22, 2026	Jul. 02, 2026	Feb. 06, 2026	Dec. 11, 2025	Dec. 10, 2025	Aug. 25, 2025	May 18, 2025	Jul. 17, 2026
Public Utilities, General Disclosures [Line Items]
Penalty issued					$ 100,000
TXNM
Public Utilities, General Disclosures [Line Items]
Number of cancelling shares (in shares)		8,000,000
Payment to unwind stock purchase agreement		$ 400,000,000.0		$ 400,000,000.0
Payment to refund dividends received			$ 13,300,000
TXNM \| TXNM 2026 Delayed-Draw Term Loan \| Bonds
Public Utilities, General Disclosures [Line Items]
Aggregate principal amount											$ 400,000,000.0
Merger Agreement \| TXNM
Public Utilities, General Disclosures [Line Items]
Purchase of common stock										$ 400,000,000.0
Merger Agreement \| NMPRC \| TXNM
Public Utilities, General Disclosures [Line Items]
Rate credits	$ 220,000,000.0								$ 105,000,000.0
Residential rate credits, payment period	10 years								4 years
Contribution to fund	$ 15,000,000.0								$ 10,000,000.0
Contribution payment period	10 years								10 years
Economic development fund									$ 35,000,000.0
Development fund payment period									10 years
Commitment to innovative technologies	$ 25,000,000.0								$ 25,000,000.0
Financial contributions to help train and build new workforce and fund economic development projects in local communities	$ 40,000,000.0
Purchase of common stock										$ 400,000,000.0
Merger Agreement \| PUCT \| TXNM
Public Utilities, General Disclosures [Line Items]
Rate credits						$ 35,000,000.0	$ 45,500,000	$ 35,000,000.0
Residential rate credits, payment period						4 years	4 years
Contribution to fund							$ 5,000,000.0
Economic development fund						$ 10,000,000.0	$ 10,000,000.0
Development fund payment period						10 years
Additional community support						$ 5,000,000.0
Charitable fund payment period						10 years