Investments (Details 2) - USD ($) $ in Millions	Jun. 30, 2017	Sep. 30, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	$ 1,176.1	$ 902.8
Short-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	1,065.2	902.8
Other Assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	$ 110.9	$ 0.0