Retirement and Postretirement Plans (Defined Benefit Plans) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 1.5	$ 1.2	$ 2.9	$ 2.5
Interest cost	2.4	2.7	4.9	5.4
Expected return on plan assets	(3.6)	(3.2)	(7.3)	(6.5)
Amortization of unrecognized prior service cost, net	0.0	0.0	0.1	0.1
Amortization of net loss	1.6	1.2	3.1	2.3
Net pension expense	$ 1.9	$ 1.9	$ 3.7	$ 3.8