Long-term and Short-term Debt - Schedule of Carrying Amounts and Estimated Fair Values (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Carrying Value
Long-term debt	$ 3,464.6	$ 1,974.7
Carrying Value
Carrying Value
Long-term debt	3,464.6	1,974.7
Fair Value
Fair Value
Long-term debt	$ 3,874.8	$ 2,497.7

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_LongTermDebtNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant