Accumulated Other Comprehensive Income (Loss) Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, net	$ (32.5)		$ (32.5)		$ (33.1)
Other comprehensive loss	0.3	$ (4.9)	0.6	$ (8.7)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, net	(29.9)		(29.9)		(30.5)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			0.6
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, net	(2.6)		(2.6)		(2.6)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			0.0
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, net	(32.5)		(32.5)		$ (33.1)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax			0.6
Other comprehensive loss	$ 0.3	$ (4.9)	$ 0.6	$ (8.7)