Regulatory and Rate Matters - TNMP (Narrative) (Details) customer in Thousands, $ in Thousands							12 Months Ended
	Jan. 24, 2025 USD ($)	Oct. 24, 2024 USD ($)	Jul. 08, 2024 customer	Mar. 01, 2024 USD ($)	Mar. 01, 2023 USD ($)	Mar. 01, 2022 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 11, 2024 USD ($)	Aug. 28, 2024 USD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory disallowances							$ 8,980	$ 71,923	$ 832
Subsequent Event
Public Utilities, General Disclosures [Line Items]
Requested increase annual distribution revenue requirement	$ 11,500
Incremental distribution investments	$ 83,500
TNMP
Public Utilities, General Disclosures [Line Items]
Regulatory disallowances							1,200
TNMP \| System Resiliency Plan
Public Utilities, General Disclosures [Line Items]
Investment owned, balance, principal amount										$ 565,800	$ 600,000
Investment owned, cost										$ 128,200	$ 151,000
Proposed plan investments (as a percent)										94.00%
TNMP \| Hurricane
Public Utilities, General Disclosures [Line Items]
Number of customers without power due to natural disaster \| customer			116
Utility plant incurred cost without power due to natural disaster							53,100
TNMP \| Hurricane \| Public Utilities, Property, Plant and Equipment, Plant in Service
Public Utilities, General Disclosures [Line Items]
Utility plant incurred cost without power due to natural disaster							32,100
TNMP \| Hurricane \| Other Deferred Costs Net Including Deferred Finance Costs
Public Utilities, General Disclosures [Line Items]
Utility plant incurred cost without power due to natural disaster							$ 21,000
TNMP \| Energy efficiency costs
Public Utilities, General Disclosures [Line Items]
Aggregate collection amount		$ 7,000
Performance bonus		$ 1,300		$ 1,200	$ 1,900	$ 2,300