Retirement Benefits - Amounts Recognized in Accumulated Other Comprehensive Loss (Details) $ in Millions	12 Months Ended
Sep. 30, 2017 USD ($)
Compensation and Retirement Disclosure [Abstract]
Balance at September 30, 2016	$ 0.0
Converted on October 1, 2016	(6.2)
Net loss amortized during the year	0.4
Net gain during the year	3.7
Non-controlling interest	(0.1)
Balance at September 30, 2017	$ (2.2)

The total of net gain (loss), prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669646-108580

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Amount after tax and reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans, attributable to noncontrolling interest.

+ References

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Amount after tax of (increase) decrease in the value of the projected benefit obligation related to a change in an actuarial assumption and increase (decrease) in the value of the plan assets resulting from experience different from that assumed, that has not been recognized in net periodic benefit (cost) credit.

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Amount after tax of reclassification adjustment from accumulated other comprehensive income (loss) for actuarial gain (loss) related to pension and other postretirement benefit plans.

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Amount after tax of reclassification adjustment from accumulated other comprehensive income (loss) for net transition asset (obligation) related to pension and other postretirement benefit plans.

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