Summary of Significant Accounting Policies - Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 390.9	$ 313.8
Property, Plant and Equipment, Net	195.4	146.9
Accumulated depreciation	(195.5)	(166.9)
Depreciation	50.8	50.3	$ 36.6
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 166.7	115.7
Building and Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Building and Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
2510 Household Furniture [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Property, Plant and Equipment, Gross	$ 101.0	97.2
Office furniture [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 85.4	74.2
Office furniture [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Office furniture [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 37.8	26.7
Financial Services [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Net	$ 55.9	$ 22.1