Accumulated Other Comprehensive Income (Loss) (Details 2) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Employee Pension and Postretirement Benefits, Net of Tax
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Tax provision (benefit)	$ (0.2)	$ (0.2)	$ (0.1)	$ (0.4)
Net of tax	0.1	0.5	0.1	1.0
Total before tax	0.3	0.7	0.2	1.4
Prior service costs
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	0.2	0.2	0.2	0.4
Actuarial (gains) losses
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	$ 0.1	$ 0.5	$ 0.0	$ 1.0