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v3.25.0.1

Short-term Borrowings and Long-term Debt - Narrative (Details) $ / shares in Units, $ in Millions |  | 1 Months Ended | 12 Months Ended
--- | --- | --- | ---
Aug. 01, 2023 $ / shares | Oct. 31, 2024 USD ($) | Aug. 31, 2024 USD ($) lawsuit | Dec. 31, 2024 USD ($) period shares
Debt Instrument [Line Items] |  |  |  |
Debt instrument, convertible, conversion ratio | 27.1278 |  |  |
Conversion price percentage | 25.00% |  |  |
Houston Electric |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Aggregate Principal |  |  |  | $ 1,400
Additional first mortgage bonds and general mortgage bonds that could be issued |  |  |  | $ 4,700
SIGECO |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Percentage of property additions |  |  |  | 70.00%
Long-term debt, gross |  |  |  | $ 985
Additional debt issuable |  |  |  | $ 899
Maximum |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, convertible, conversion ratio |  |  |  | 33.9097
Debt instrument, convertible, number of equity instruments (in shares) | shares |  |  |  | 33,909,700
Junior Subordinated Notes | Maximum |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Deferral period | period |  |  |  | 20
Convertible Debt |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, convertible, conversion price (in dollar per shares) | $ / shares | $ 36.86 |  |  |
Debt instrument, redemption price (as a percent) | 100.00% |  |  |
General mortgage bonds, 2.35% to 6.95%, due 2026 to 2053 | Houston Electric |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Secured debt |  |  |  | $ 8,400
Bonds Pollution Control Due | Houston Electric |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Secured debt |  |  |  | $ 68
Percentage of property additions |  |  |  | 70.00%
Series A Junior Subordinated Notes Due 2055 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Aggregate Principal |  |  | $ 400 |
Series B Junior Subordinated Notes Due 2055 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Aggregate Principal |  |  | $ 400 |
Series A, 7 Point Zero Percent, Junior Subordinated Notes Due 2030 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Basis spread (as a percent) |  |  | 7.00% |
Debt Instrument, interest rate, period |  |  | 5 years |
Number of days before interest rate period | lawsuit |  |  | 2 |
Series A, 3 Point 254 Percent, Junior Subordinated Notes Due 2030 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Basis spread (as a percent) |  |  | 3.254% |
Series B, 6 Point 850 Percent, Junior Subordinated Notes Due 2030 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Basis spread (as a percent) |  |  | 6.85% |
Series A Junior Subordinated Notes Due 2035 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, interest rate, period |  |  | 5 years |
Number of days before interest rate period | lawsuit |  |  | 2 |
Series B, 2 Point 946 Percent, Junior Subordinated Notes Due 2030 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Basis spread (as a percent) |  |  | 2.946% |
Series C Junior Subordinated Notes Due 2055 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Aggregate Principal |  | $ 500 |  |
Series A, 6 Point 700 Percent, Junior Subordinated Notes Due 2030 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Basis spread (as a percent) |  | 6.70% |  |
Series A, 2 Point 586 Percent, Junior Subordinated Notes Due 2030 | Junior Subordinated Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Basis spread (as a percent) |  | 2.586% |  |

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