Retirement Benefits (Narrative) (Details) - Defined Benefit Pension Plan - USD ($) $ in Millions	3 Months Ended				9 Months Ended		12 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Company contributions					$ 31.0	$ 43.0	$ 68.3
Pension settlement loss					6.3
Minimum
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year	$ 45.0				45.0
Maximum
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year	65.0				65.0
International
Defined Benefit Plan Disclosure [Line Items]
Pension settlement loss	$ 0.0			$ 0.0	$ 0.2	$ 0.0
Prior service cost arising during period			$ 4.7
U.S. Supplementary Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Pension settlement loss		$ 5.0