Retirement Benefits (Narrative) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Company contributions	$ 43.0	$ 57.0	$ 64.1
Minimum
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year	50.0
Maximum
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year	$ 70.0
Discontinued Operations
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 1.3