Retirement Benefits (Plan Assets Target Allocation) (Details) - Defined Benefit Pension Plan	Sep. 30, 2021	Sep. 30, 2020
U.S.
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	100.00%	100.00%
U.S. | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	30.00%	51.00%
U.S. | Bonds (government and corporate)
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	64.00%	43.00%
U.S. | Real estate/other
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	6.00%	5.00%
U.S. | Cash
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	0.00%	1.00%
U.S. | Minimum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	20.00%
U.S. | Minimum | Bonds (government and corporate)
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	61.00%
U.S. | Minimum | Real estate/other
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	0.00%
U.S. | Minimum | Cash
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	0.00%
U.S. | Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	35.00%
U.S. | Maximum | Bonds (government and corporate)
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	76.00%
U.S. | Maximum | Real estate/other
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	10.00%
U.S. | Maximum | Cash
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	0.00%
International
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	100.00%	100.00%
International | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	36.00%	43.00%
International | Bonds (government and corporate)
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	63.00%	56.00%
International | Real estate/other
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	0.00%	0.00%
International | Cash
Defined Benefit Plan Disclosure [Line Items]
Actual allocation (percent)	1.00%	1.00%
International | Minimum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	29.00%
International | Minimum | Bonds (government and corporate)
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	62.00%
International | Minimum | Real estate/other
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	0.00%
International | Minimum | Cash
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	2.00%
International | Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	38.00%
International | Maximum | Bonds (government and corporate)
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	71.00%
International | Maximum | Real estate/other
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	0.00%
International | Maximum | Cash
Defined Benefit Plan Disclosure [Line Items]
Target allocation (percent)	2.00%