Borrowings - Schedule of Components of the Carrying Value of Notes (Details) - USD ($) |
Jun. 30, 2026 |
Sep. 30, 2025 |
Feb. 27, 2025 |
Aug. 15, 2023 |
May 18, 2021 |
|---|---|---|---|---|---|
| Debt Instrument [Line Items] | |||||
| Unamortized financing costs | $ (4,954,000) | $ (6,561,000) | |||
| Net carrying value | 1,438,842,000 | 1,486,880,000 | |||
| 2027 Notes | |||||
| Debt Instrument [Line Items] | |||||
| Principal | 350,000,000.0 | 350,000,000.0 | $ 350,000,000.0 | ||
| Unamortized financing costs | (500,000) | (1,000,000.0) | |||
| Unaccreted discount | (100,000) | (200,000) | $ (1,000,000.0) | ||
| Interest rate swap fair value adjustment | (5,900,000) | (12,200,000) | |||
| Net carrying value | 343,500,000 | 336,600,000 | |||
| Fair Value | 345,300,000 | 339,800,000 | |||
| 2029 Notes | |||||
| Debt Instrument [Line Items] | |||||
| Principal | 300,000,000.0 | 300,000,000.0 | $ 300,000,000.0 | ||
| Unamortized financing costs | (1,700,000) | (2,200,000) | |||
| Unaccreted discount | (1,700,000) | (2,100,000) | $ (3,500,000) | ||
| Interest rate swap fair value adjustment | (800,000) | 4,800,000 | |||
| Net carrying value | 295,800,000 | 300,500,000 | |||
| Fair Value | 305,800,000 | 314,500,000 | |||
| 2030 Notes | |||||
| Debt Instrument [Line Items] | |||||
| Principal | 300,000,000.0 | 300,000,000.0 | $ 300,000,000.0 | ||
| Unamortized financing costs | (2,800,000) | (3,300,000) | |||
| Unaccreted discount | 0 | 0 | $ (100,000) | ||
| Interest rate swap fair value adjustment | 1,300,000 | 8,100,000 | |||
| Net carrying value | 298,500,000 | 304,800,000 | |||
| Fair Value | $ 298,500,000 | $ 301,100,000 |
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- Definition Face (par) amount of debt instrument at time of issuance. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount, after accumulated amortization, of debt discount. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of all derivatives designated as interest rate fair value hedging instruments. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset. No definition available.
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