(Components of Long-Term Debt Including Associated Interest Rates and Related Fair Values) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Total	$ 11,238.5	$ 9,548.4
Total, Estimated Fair Value	11,725.0	9,322.0
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	(85.2)	(69.3)
Hedging Liabilities, Noncurrent	5.8	(39.0)
Total, Carrying Value, net of aggregate unamortized discount	11,159.1	9,440.1
Two Point Zero Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 0.0	350.0
Stated Interest Rate	2.00%
Effective Interest Rate	2.012%
Two Point Two Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500.0	500.0
Stated Interest Rate	2.20%
Effective Interest Rate	2.228%
Two Point Four Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500.0	500.0
Stated Interest Rate	2.45%
Effective Interest Rate	2.511%
Three Point Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 600.0	600.0
Stated Interest Rate	3.50%
Effective Interest Rate	3.529%
Four Point Zero Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 750.0	750.0
Stated Interest Rate	4.00%
Effective Interest Rate	3.958%
Three Point Five Five Percentage Senior Notes [Member] [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,000.0	0.0
Stated Interest Rate	3.55%
Effective Interest Rate	3.871%
Two Point One Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500.0	500.0
Debt Instrument, Face Value from Reopening of Previous Issuance	$ 250.0	250.0
Stated Interest Rate	2.10%
Effective Interest Rate	2.293%
Effective Interest Rate for Reopening of Previous Issuance	1.60%
Two Point Seven Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500.0	500.0
Stated Interest Rate	2.70%
Effective Interest Rate	2.819%
Three Point Eight Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 750.0	750.0
Stated Interest Rate	3.85%
Effective Interest Rate	2.859%
Three Point One Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,000.0	1,000.0
Stated Interest Rate	3.10%
Effective Interest Rate	3.107%
PointThreeSevenTwoPercentageYenDenominatedSeniorNotes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 788.5	748.4
Stated Interest Rate	0.372%
Effective Interest Rate	0.462%
Three Point Eight Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,250.0	1,250.0
Stated Interest Rate	3.80%
Effective Interest Rate	3.721%
Four Point Three Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 350.0	350.0
Stated Interest Rate	4.30%
Effective Interest Rate	4.348%
Three Point Seven Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500.0	500.0
Stated Interest Rate	3.75%
Effective Interest Rate	3.765%
Four Point Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,000.0	1,000.0
Stated Interest Rate	4.50%
Effective Interest Rate	4.504%
Four Point Four Five Percentage Senior Notes [Member] [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,000.0	0.0
Stated Interest Rate	4.45%
Effective Interest Rate	4.433%
Fair Value, Inputs, Level 2 [Member] \| Two Point Zero Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	$ 0.0	350.0
Fair Value, Inputs, Level 2 [Member] \| Two Point Two Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	499.0	490.0
Fair Value, Inputs, Level 2 [Member] \| Two Point Four Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	494.0	451.0
Fair Value, Inputs, Level 2 [Member] \| Three Point Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	630.0	576.0
Fair Value, Inputs, Level 2 [Member] \| Four Point Zero Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	815.0	754.0
Fair Value, Inputs, Level 2 [Member] \| Three Point Five Five Percentage Senior Notes [Member] [Member]
Debt Instrument [Line Items]
Estimated Fair Value	1,048.0	0.0
Fair Value, Inputs, Level 2 [Member] \| Two Point One Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	499.0	489.0
Estimated Fair Value from Reopening of Previous Issuance	249.0	244.0
Fair Value, Inputs, Level 2 [Member] \| Two Point Seven Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	506.0	486.0
Fair Value, Inputs, Level 2 [Member] \| Three Point Eight Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	789.0	759.0
Fair Value, Inputs, Level 2 [Member] \| Three Point One Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	1,024.0	986.0
Fair Value, Inputs, Level 2 [Member] \| PointThreeSevenTwoPercentageYenDenominatedSeniorNotes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	791.0	743.0
Fair Value, Inputs, Level 2 [Member] \| Three Point Eight Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	1,334.0	1,249.0
Fair Value, Inputs, Level 2 [Member] \| Four Point Three Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	368.0	330.0
Fair Value, Inputs, Level 2 [Member] \| Three Point Seven Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	489.0	438.0
Fair Value, Inputs, Level 2 [Member] \| Four Point Five Percentage Senior Notes [Member]
Debt Instrument [Line Items]
Estimated Fair Value	1,089.0	977.0
Fair Value, Inputs, Level 2 [Member] \| Four Point Four Five Percentage Senior Notes [Member] [Member]
Debt Instrument [Line Items]
Estimated Fair Value	$ 1,101.0	$ 0.0

Face (par) amount of debt instrument from reopening of previous debt issuance.

No definition available.

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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable related to reopening of previous debt issuance.

+ References

No definition available.

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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 related to reopening of previous issuance.

+ References

No definition available.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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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.

+ References

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- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

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- Definition

Fair value of liability arising from a financial instrument or contract used to mitigate a specified risk (hedge), expected to be settled after one year or beyond the normal operating cycle, if longer.

+ References

No definition available.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

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