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Financial Instruments (Narrative) (Details) Bcf in Billions | 3 Months Ended | 6 Months Ended | 12 Months Ended | 36 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Mar. 31, 2024 USD ($) counterparty Bcf | Mar. 31, 2024 USD ($) counterparty Bcf | Dec. 31, 2023 USD ($) | Dec. 31, 2025 USD ($) payment | Sep. 30, 2023 USD ($) | Mar. 31, 2023 USD ($) | Sep. 30, 2022 USD ($)
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
Foreign Currency Forward Contract Hedge Duration |  | 7 years |  |  |  |  |
After tax net hedging gains in accumulated other comprehensive income (loss) | $ 135,000,000 | $ 135,000,000 |  |  |  |  |
After Tax Net Hedging Gains Reclassified Within Twelve Months |  | 100,900,000 |  |  |  |  |
Fair market value of derivative liability with a credit-risk related contingency | 0 | 0 |  |  |  |  |
Hedging Collateral Deposits | 0 | 0 |  |  | $ 0 | $ 0 | $ 91,670,000
California Asset Sale | Forecast |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
Maximum Annual Contingent Payment |  |  |  | $ 10,000,000 |  |  |
Amount of Each Incremental Contingency Payment |  |  |  | 1,000,000 |  |  |
Incremental price, exceeding ICE Brent Average Price (in dollars per barrel) |  |  |  | 1 |  |  |
California Asset Sale | Present Value of Contingent Consideration |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
Value of Contingent Consideration Received from Sale of Assets | 3,600,000 | 3,600,000 |  |  | $ 7,300,000 |  |
California Asset Sale | Mark to Market of Contingent Consideration |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
Mark-to-Market Adjustment for Contingent Consideration | $ 500,000 | $ (3,700,000) |  |  |  |  |
California Asset Sale | Minimum |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
ICE Brent Average (in dollars per barrel) |  |  | $ 95 |  |  |  |
California Asset Sale | Minimum | Forecast |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
ICE Brent Average (in dollars per barrel) |  |  |  | $ 95 |  |  |
California Asset Sale | Maximum | Forecast |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
Number Of Annual Contingent Payments | payment |  |  |  | 3 |  |  |
ICE Brent Average (in dollars per barrel) |  |  |  | $ 105 |  |  |
Cash Flow Hedges |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
Hedge Duration |  | 5 years |  |  |  |  |
Over the Counter Swaps, No Cost Collars and Foreign Currency Forward Contracts |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
Number of counterparties in which the company holds over-the-counter swap positions | counterparty | 19 | 19 |  |  |  |  |
Number of counterparties in net gain position | counterparty | 19 | 19 |  |  |  |  |
Credit risk exposure per counterparty | $ 10,100,000 | $ 10,100,000 |  |  |  |  |
Maximum Credit Risk Exposure Per Counterparty |  | 33,200,000 |  |  |  |  |
Collateral Received by the Company | $ 0 | $ 0 |  |  |  |  |
Number of counterparties with a common credit-risk related contingency | counterparty | 16 | 16 |  |  |  |  |
Hedging Collateral Deposits | $ 0 | $ 0 |  |  |  |  |
Natural Gas Bcf | Cash Flow Hedges |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
Nonmonetary notional amount of price risk cash flow hedge derivatives, natural gas | Bcf | 351.2 | 351.2 |  |  |  |  |
Foreign Currency Contracts |  |  |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |  |  |
Hedging Notional Amount of Forecasted Transportation Costs | $ 50,400,000 | $ 50,400,000 |  |  |  |  |

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