Retirement Benefits (Details 8) (USD $) In Millions, unless otherwise specified	12 Months Ended
Sep. 30, 2012	Sep. 30, 2011
One percentage point change in assumed health care cost trend rates
Increase to total of service and interest cost components	$ 0.2	$ 0.2
Decrease to total of service and interest cost components	(0.2)	(0.1)
Increase to postretirement benefit obligation	2.4	2.7
Decrease to postretirement benefit obligation	(2.1)	(2.4)
Pension plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	3,850.4	3,064.4
Accumulated benefit obligation	3,573.5	2,876.2
Fair value of plan assets	$ 2,919.0	$ 2,172.7

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Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

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Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

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The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The effect of a one-percentage-point increase in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

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If aggregate disclosures are presented, the aggregate pension accumulated benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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If aggregate disclosures are presented, the aggregate fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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If aggregate disclosures are presented, the aggregate projected benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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