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v3.25.1

Capitalization (Narrative) (Details) $ / shares in Units, $ in Thousands |  |  |  | 6 Months Ended |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 06, 2025 USD ($) | Feb. 28, 2025 USD ($) | Feb. 19, 2025 USD ($) | Mar. 31, 2025 USD ($) $ / shares shares | Mar. 31, 2024 USD ($) | Jan. 31, 2025 USD ($) | Jan. 30, 2025 bank | Sep. 30, 2024 USD ($) | Apr. 30, 2024 USD ($) | Mar. 08, 2024 USD ($) | Feb. 14, 2024 USD ($) lender | Sep. 30, 2023 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Stock repurchase program, authorized amount |  |  |  |  |  |  |  |  |  | $ 200,000 |  |
Share repurchases (in shares) | shares |  |  |  | 608,295 |  |  |  |  |  |  |  |
Current Portion of Long-Term Debt |  |  |  | $ 350,000 |  |  |  | $ 500,000 |  |  |  |
Cash Held in Trust for Bondholders |  |  |  | 51,352 | $ 0 |  |  | 0 |  |  |  | $ 0
Repayments of long-term debt |  |  |  | 954,086 | 0 |  |  |  |  |  |  |
Net Proceeds from Issuance of Long-Term Debt |  |  |  | 989,019 | 0 |  |  |  |  |  |  |
Premiums Paid on Early Redemption of Debt |  |  |  | (2,385) | $ 0 |  |  |  |  |  |  |
Unamortized Debt Expense |  |  |  | 7,166 |  |  |  | 5,604 |  |  |  |
5.50% Notes Due March 15, 2030 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt, interest rate | 5.50% |  | 5.50% |  |  |  |  |  |  |  |  |
Long-term debt, face amount |  |  | $ 500,000 |  |  |  |  |  |  |  |  |
Net Proceeds from Issuance of Long-Term Debt |  |  | $ 495,400 |  |  |  |  |  |  |  |  |
Percentage of principal amount |  |  | 101.00% |  |  |  |  |  |  |  |  |
Maximum interest rate adjustment |  |  | 2.00% |  |  |  |  |  |  |  |  |
5.50% Notes Due March 15, 2030 | Maximum |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt, interest rate |  |  | 7.50% |  |  |  |  |  |  |  |  |
5.95% Notes Due March 15, 2035 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt, interest rate |  |  | 5.95% |  |  |  |  |  |  |  |  |
Long-term debt, face amount |  |  | $ 500,000 |  |  |  |  |  |  |  |  |
Net Proceeds from Issuance of Long-Term Debt |  |  | $ 493,600 |  |  |  |  |  |  |  |  |
Percentage of principal amount |  |  | 101.00% |  |  |  |  |  |  |  |  |
Maximum interest rate adjustment |  |  | 2.00% |  |  |  |  |  |  |  |  |
5.95% Notes Due March 15, 2035 | Maximum |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt, interest rate |  |  | 7.95% |  |  |  |  |  |  |  |  |
5.50% Notes Due January 2026 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt, interest rate | 5.50% |  |  |  |  |  |  |  |  |  |  |
Long-term debt, face amount | $ 500,000 |  |  |  |  |  |  |  |  |  |  |
Debt instrument redeemed | 503,300 |  |  |  |  |  |  |  |  |  |  |
5.50% Notes Due January 2026 | Exploration and Production and Gathering |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Paid on Early Redemption of Debt | 1,800 |  |  |  |  |  |  |  |  |  |  |
5.50% Notes Due January 2026 | Pipeline and Storage |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Unamortized Debt Expense | 1,500 |  |  |  |  |  |  |  |  |  |  |
Indenture From 1974 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Cash Held in Trust for Bondholders |  |  |  |  |  | $ 53,200 |  |  |  |  |  |
Carrying amount of long-term debt |  |  |  | $ 50,000 |  |  |  |  |  |  |  |
Long term debt, interest payments remaining, value |  |  |  |  |  | $ 3,200 |  |  |  |  |  |
Interest payment |  | $ 1,800 |  |  |  |  |  |  |  |  |  |
Share Repurchase Plan |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Share repurchases (in shares) | shares |  |  |  | 774,768 |  |  |  |  |  |  |  |
Share repurchase program, average cost per share (in dollars per share) | $ / shares |  |  |  | $ 63.74 |  |  |  |  |  |  |  |
Share repurchases |  |  |  | $ 49,800 |  |  |  |  |  |  |  |
Credit Agreement |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Number of banks In syndicate | bank |  |  |  |  |  |  | 11 |  |  |  |  |
Maximum borrowing capacity |  |  |  | 1,000,000 |  |  |  |  |  |  |  |
Extended term of credit agreement |  |  |  |  |  |  | 1 year |  |  |  |  |
7.38% Notes Due June 2025 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Current Portion of Long-Term Debt |  |  |  | $ 50,000 |  |  |  | $ 50,000 |  |  |  |
Long-term debt, interest rate |  |  |  | 7.38% |  |  |  | 7.38% |  |  |  |
7.38% Notes Due June 2025 | Principal |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Cash Held in Trust for Bondholders |  |  |  | $ 50,000 |  |  |  |  |  |  |  |
5.20% Notes Due July 2025 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Current Portion of Long-Term Debt | $ 450,000 |  |  |  |  |  |  | $ 450,000 |  |  |  |
Long-term debt, interest rate | 5.20% |  |  |  |  |  |  | 5.20% |  |  |  |
Long-term debt, face amount | $ 450,000 |  |  |  |  |  |  |  |  |  |  |
Debt instrument redeemed | 450,800 |  |  |  |  |  |  |  |  |  |  |
5.20% Notes Due July 2025 | Exploration and Production and Gathering |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Premiums Paid on Early Redemption of Debt | 600 |  |  |  |  |  |  |  |  |  |  |
5.20% Notes Due July 2025 | Pipeline and Storage |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Unamortized Debt Expense | $ 200 |  |  |  |  |  |  |  |  |  |  |
Term Loan Agreement |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  | 300,000 |  |  |  |  |  |  | $ 300,000 |
Long-term debt, face amount |  |  |  |  |  |  |  |  | $ 300,000 |  |  |
Number of lenders | lender |  |  |  |  |  |  |  |  |  |  | 6 |
Proceeds from debt, net of issuance costs |  |  |  | $ 299,400 |  |  |  |  |  |  |  |
Rate adjustment to SOFR |  |  |  | 0.0010 |  |  |  |  |  |  |  |
Spread on variable rate |  |  |  | 1.375% |  |  |  |  |  |  |  |
Term Loan Agreement | 5.79% Through May 2025 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt, variable interest rate |  |  |  | 5.79% |  |  |  |  |  |  |  |

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