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Winter Storm Uri (Details) - USD ($) $ in Thousands |  |  |  |  | 1 Months Ended | 6 Months Ended | 7 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 23, 2023 | Mar. 09, 2023 | Mar. 03, 2023 | Oct. 25, 2022 | Feb. 28, 2021 | Mar. 31, 2023 | Mar. 31, 2022 | Mar. 31, 2023 | Sep. 30, 2022 | Mar. 31, 2021
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Aggregate natural gas purchases |  |  |  |  | $ 2,300,000 |  |  |  |  |
Repayment of senior notes |  |  |  |  |  | $ 2,200,000 | $ 200,000 |  |  |
Regulatory assets |  |  |  |  |  | 513,931 |  | $ 513,931 | $ 2,605,372 |
Winter Storm Uri incremental costs |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  |  |  | 121,493 |  | 121,493 | $ 2,109,454 |
Winter Storm Uri incremental costs | Winter Storm Uri | Kansas |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  |  |  | $ 89,100 |  | 89,100 |  |
Winter Storm Uri incremental costs | Winter Storm Uri | Texas |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Regulatory asset, deferred costs |  |  |  |  |  |  |  | $ 32,400 |  |
Extraordinary Gas Cost | Winter Storm Uri | Kansas |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Regulatory asset, authorized |  |  |  | $ 118,500 |  |  |  |  |  |
Regulatory asset, amortization period |  |  |  | 12 years |  |  |  |  |  |
Extraordinary Gas Cost | Winter Storm Uri | Texas |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Regulatory asset, authorized | $ 3,500,000 |  |  |  |  |  |  |  |  |
Proceeds from customer rate relief bonds | 2,020,000 |  |  |  |  |  |  |  |  |
Regulatory asset, relieved | $ 2,020,000 |  |  |  |  |  |  |  |  |
Extraordinary Gas Cost | Winter Storm Uri | Texas | Minimum |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Regulatory asset, maturity period | 12 years |  |  |  |  |  |  |  |  |
Extraordinary Gas Cost | Winter Storm Uri | Texas | Maximum |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Regulatory asset, maturity period | 18 years |  |  |  |  |  |  |  |  |
Senior Notes |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  | $ 2,200,000
Repayment of senior notes |  |  | $ 2,200,000 |  |  |  |  |  |  |
Unsecured Debt | Line of Credit |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Repayment of senior notes |  | $ 1,100,000 |  |  |  |  |  |  |  |
Unsecured Senior Term Loan Due 2023 | Unsecured Debt | Line of Credit |  |  |  |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  | $ 2,020,000 |  |  |  |  |  |  |

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