Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, net	$ (24.6)	$ (17.5)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(7.4)	(4.0)	$ (4.6)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	0.2	1.5	0.8
Net unrealized gain on available-for-sale securities	0.0	2.7	0.2
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax	0.5	0.3	0.2
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax - AFS securities		(3.3)
Other Comprehensive Income (Loss), Net of Tax	(7.1)	(5.9)	(5.2)
Deferred Tax Liabilities, Accumulated Other Comprehensive Income - AFS Securities		2.0
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, net	(20.1)	(12.7)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(7.4)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax	0.0
Other Comprehensive Income (Loss), Net of Tax	(7.4)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, net	(4.5)	(4.8)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	(0.2)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax	0.5
Other Comprehensive Income (Loss), Net of Tax	0.3
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, net	(24.6)	(17.5)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(7.6)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.5
Other Comprehensive Income (Loss), Net of Tax	$ (7.1)	$ (5.9)	$ (5.2)