Income Taxes - Components of Provision for Income 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
Current Tax Provision
Federal									$ 0.0	$ 0.0	$ 0.0
State									0.6	0.5	0.5
Foreign									58.3	31.6	28.0
Current Income Tax Provision									58.9	32.1	28.5
Deferred Tax Provision
Federal									1.3	1.4	0.9
State									0.1	0.1	0.2
Foreign									(1.5)	(1.9)	2.3
Deferred Income Tax Provision									(0.1)	(0.4)	3.4
Income Tax Expense	$ 15.6	$ 17.6	$ 12.2	$ 13.4	$ 3.6	$ 10.8	$ 11.2	$ 6.1	$ 58.8	$ 31.7	$ 31.9