Retirement and Postretirement Benefit Plans (Schedule of Net Periodic Benefit Cost) (Details) - Pension Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4.5	$ 4.8
Interest cost	12.5	11.0	$ 9.9
Expected return on plan assets	(14.8)	(15.7)	(14.6)
Amortization of unrecognized prior service cost, net	0.1	0.1	0.2
Amortization of net loss	2.4	4.5	6.1
Net periodic benefit cost	4.7	4.7	7.4
Special termination benefits	0.0	0.0	0.1
Net pension expense	4.7	4.7	7.5
Selling, General and Administrative Expenses [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2.7	3.2	3.8
Cost of Sales [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.8	$ 1.6	$ 2.0