Commitments and Contingencies - Legal Claims and Insurance (Details) - USD ($) $ in Millions	9 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Rollforward of reserves for legal claims
Reserves for legal claims, beginning of period	$ 408.1	$ 420.6
Increase in reserves	45.5	47.2
Payments	(12.7)	(60.0)
Reserves for legal claims, end of period	$ 440.9	$ 407.8

Amount of loss contingency liability.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14326-108349

+ Details

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

- Definition

Amount of increase (decrease) in loss contingency liability.

+ References

+ Details

Name:	us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash outflow reducing loss contingency liability.

+ References

+ Details

Name:	us-gaap_LossContingencyAccrualPayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_LossContingencyAccrualRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration