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Debt - Narrative (Details) |  | 6 Months Ended |
--- | --- | --- | ---
Oct. 01, 2024 USD ($) | Mar. 31, 2025 USD ($) credit_facility | Mar. 31, 2024 USD ($) | Sep. 30, 2024 USD ($)
Line Of Credit Facility [Line Items] |  |  |  |
Proceeds from issuance of long-term debt |  | $ 645,372,000 | $ 898,275,000 |
Maximum debt-to-total-capitalization ratio |  | 70.00% |  |
Debt-to-total-capitalization ratio |  | 0.40 |  |
Minimum |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Outstanding indebtedness |  | $ 15,000,000 |  |
Maximum |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Outstanding indebtedness |  | $ 100,000,000 |  |
Unsecured 5.00% Senior Notes, due December 2054 |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Interest rate |  | 5.00% |  |
Unsecured 5.00% Senior Notes, due December 2054 | Senior Notes |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Debt face amount | $ 650,000,000 |  |  |
Interest rate | 5.00% |  |  |
Effective rate | 3.90% |  |  |
Proceeds from issuance of long-term debt | $ 639,400,000 |  |  |
Five Year Unsecured Revolving Credit Agreement | Commercial Paper |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Maximum borrowing capacity |  | $ 1,500,000,000 |  |
Debt agreement term |  | 5 years |  |
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Outstanding commercial paper |  | $ 0 |  | $ 0
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Minimum | Base Rate |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Interest rate spread |  | 0.00% |  |
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Minimum | Term SOFR |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Interest rate spread |  | 0.75% |  |
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Maximum | Base Rate |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Interest rate spread |  | 0.25% |  |
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Maximum | Term SOFR |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Interest rate spread |  | 1.25% |  |
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Commercial Paper |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Maximum borrowing capacity |  | $ 1,500,000,000 |  |
Accordion feature |  | 250,000,000 |  |
Maximum borrowing capacity post accordion feature |  | 1,750,000,000 |  |
Five Year Unsecured Revolving Credit Agreement, March 28, 2029 | Revolving Credit Facility |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Maximum borrowing capacity |  | $ 3,100,000,000 |  |
Number of credit facilities | credit_facility |  | 4 |  |
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Maximum borrowing capacity |  | $ 1,500,000,000 |  |
Debt agreement term |  | 3 years |  |
Accordion feature |  | $ 250,000,000 |  |
Maximum borrowing capacity post accordion feature |  | 1,750,000,000 |  |
Outstanding borrowings |  | $ 0 |  | 0
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Minimum | Base Rate |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Interest rate spread |  | 0.00% |  |
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Minimum | Term SOFR |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Interest rate spread |  | 0.75% |  |
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Maximum | Base Rate |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Interest rate spread |  | 0.25% |  |
$1.5 Billion Revolving Credit Facility | Revolving Credit Facility | Maximum | Term SOFR |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Interest rate spread |  | 1.25% |  |
$50 Million Bank Loan Agreement | Line of Credit |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Maximum borrowing capacity |  | $ 50,000,000 |  |
Debt agreement term |  | 364 days |  |
Outstanding borrowings |  | $ 0 |  | $ 0
$50 Million Revolving Credit Facility |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Outstanding borrowings |  | 0 |  |
$50 Million Revolving Credit Facility | Revolving Credit Facility |  |  |  |
Line Of Credit Facility [Line Items] |  |  |  |
Maximum borrowing capacity |  | $ 50,000,000 |  |
Debt agreement term |  | 364 days |  |
Remaining borrowing capacity |  | $ 44,400,000 |  |

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- Definition Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(a)(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482949/835-30-55-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69B -Publisher FASB -URI https://asc.fasb.org/1943274/2147481568/470-20-55-69B Reference 4: http://www.xbrl.org/2003/role/exampleRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 69C -Publisher FASB -URI https://asc.fasb.org/1943274/2147481568/470-20-55-69C Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482900/835-30-50-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482925/835-30-45-2 + Details
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- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482949/835-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482900/835-30-50-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 835 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482925/835-30-45-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481139/470-20-50-6 + Details
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- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -SubTopic 10 -Topic 210 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
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- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
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