Long-term and Short-term Debt - Narrative (Details)				1 Months Ended	12 Months Ended
	Jun. 29, 2022 USD ($)	Aug. 31, 2021 USD ($)	Mar. 01, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 28, 2022 USD ($)	Mar. 31, 2020 USD ($)
Debt Instrument [Line Items]
Short-term debt					$ 94,700,000	$ 359,300,000
Interest payments					$ 133,200,000	120,400,000	$ 91,800,000
0.35% notes, payable in August 2023
Debt Instrument [Line Items]
Stated interest rate					0.00003%
2.80% notes, payable in August 2061
Debt Instrument [Line Items]
Stated interest rate					0.028%
Notes Payable, Other Payables
Debt Instrument [Line Items]
Debt instrument, face amount		$ 1,500,000,000		$ 1,000,000,000					$ 1,000,000,000
Notes Payable, Other Payables | 0.35% notes, payable in August 2023
Debt Instrument [Line Items]
Stated interest rate		0.35%
Debt instrument, face amount		$ 600,000,000
Notes Payable, Other Payables | 1.750% Notes Due August 2031
Debt Instrument [Line Items]
Stated interest rate		1.75%
Debt instrument, face amount		$ 450,000,000
Notes Payable, Other Payables | 2.80% notes, payable in August 2061
Debt Instrument [Line Items]
Stated interest rate		2.80%
Debt instrument, face amount		$ 450,000,000
Notes Payable, Other Payables | 4.200% Notes Due March 2049
Debt Instrument [Line Items]
Stated interest rate									4.20%
Debt instrument, face amount				575,000,000
Proceeds from issuance of debt		1,485,600,000		$ 987,600,000
Notes Payable, Other Payables | 3.500% Notes Due March 2029
Debt Instrument [Line Items]
Stated interest rate				3.50%
Debt instrument, face amount				$ 425,000,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity	$ 750,000,000
Debt instrument, term	5 years
Line of credit facility, current borrowing capacity	$ 1,500,000,000							$ 1,250,000,000
Maximum ratio of EBITDA to interest expense under credit facility	3.0
Treasury locks
Debt Instrument [Line Items]
Derivative, gain (loss) on derivative, net		$ 28,000,000	$ 35,700,000
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest
Interest Bearing Loan
Debt Instrument [Line Items]
Short-term debt					$ 23,500,000	42,300,000
Line of Credit
Debt Instrument [Line Items]
Borrowing capacity					75,000,000
Unsecured line of credit, amount borrowed					$ 70,000,000
Stated interest rate					6.29%
Commercial Paper
Debt Instrument [Line Items]
Short-term debt						$ 317,000,000
Debt, weighted average interest rate						303.00%
Debt instrument, term						22 days
Foreign Line of Credit
Debt Instrument [Line Items]
Borrowing capacity					$ 225,800,000
Letter of Credit
Debt Instrument [Line Items]
Borrowing capacity					$ 32,000,000