Income Taxes - Current and Deferred Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)									$ 1.3	$ 0.8	$ 0.5
Current State and Local Tax Expense (Benefit)									0.8	1.2	0.0
Current Foreign Tax Expense (Benefit)									16.8	15.4	11.6
Current Income Tax Expense (Benefit)									18.9	17.4	12.1
Deferred Income Tax Expense (Benefit)									(0.8)	5.0	(5.7)
Other Tax Expense (Benefit)									(0.1)	0.0	0.0
Income tax expense	$ 2.4	$ 6.8	$ 5.5	$ 3.3	$ 8.1	$ 5.0	$ 5.1	$ 4.2	$ 18.0	$ 22.4	$ 6.4