Retirement Benefit (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Company contribution range	3% to 7%
Voluntary contribution to U.S. qualified pension plan	$ 200.0
Recognized prior service credits	9.8
Recognized prior service credits, net of tax	6.4
Recognized net actuarial losses	155.2
Recognized net actuarial losses, net of tax	101.8
Accumulated benefit obligation for pension plans	4,252.2	$ 4,429.1
Expense related to defined contribution savings plans	41.5	38.6	$ 46.3
Defined Benefit Plan, Amounts that will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year
Prior service credits	4.9
Prior service credits, net of tax	3.5
Net actuarial losses	115.4
Net actuarial losses, net of tax	$ 75.2
United States Postretirement Benefit Plan of US Entity [Member]
Defined Benefit Plan Disclosure [Line Items]
Ultimate gross health care cost trend rate	5.50%
Year that gross health care cost trend rate will be reached	2019
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Voluntary contribution to U.S. qualified pension plan	$ 254.9	44.3
Recognized prior service credits	3.7	2.9	2.7
Recognized net actuarial losses	152.9	124.5	118.7
Estimated future payments, during next fiscal year	53.8
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Voluntary contribution to U.S. qualified pension plan	10.0	10.9
Recognized prior service credits	6.1	11.1	14.5
Recognized net actuarial losses	2.3	$ 2.3	$ 4.5
Estimated future payments, during next fiscal year	$ 9.7
Non-U.S. Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Ultimate gross health care cost trend rate	4.50%
Year that gross health care cost trend rate will be reached	2018