Debt (Bonds) (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Sep. 30, 2025 |
Jun. 30, 2025 |
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| Series 2025A Bonds, due June 2032 | |||
| Debt Instrument [Line Items] | |||
| Interest rate | 5.00% | ||
| Series 2025A Bonds, due June 2032 | Bonds | |||
| Debt Instrument [Line Items] | |||
| Principal amount | $ 400 | ||
| Debt issuance costs, net | $ 6 | ||
| Interest rate | 5.00% | ||
| Series 2025 B Bonds, due June 2032 | |||
| Debt Instrument [Line Items] | |||
| Interest rate | 4.625% | ||
| Series 2025 B Bonds, due June 2032 | Bonds | |||
| Debt Instrument [Line Items] | |||
| Principal amount | $ 100 | ||
| Debt issuance costs, net | $ 2 | ||
| Interest rate | 4.625% | ||
| Series 2026A Bonds, due June 2033 | |||
| Debt Instrument [Line Items] | |||
| Interest rate | 4.30% | ||
| Series 2026A Bonds, due June 2033 | Bonds | |||
| Debt Instrument [Line Items] | |||
| Principal amount | $ 225 | ||
| Debt issuance costs, net | $ 4 | ||
| Interest rate | 4.30% |
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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 Contractual interest rate for funds borrowed, under the debt agreement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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 issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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