Summary of Significant Accounting Policies - Schedule of Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive (loss) income	$ (95.5)	$ (38.4)	$ 106.4
Correction of Error
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive (loss) income	(10.7)
Recorded Amount Prior to Error Correction
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive (loss) income	$ (84.8)