Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2022
Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Company contributions	$ 8.0	$ 9.1	$ 44.7
Curtailment gain	1.9	0.0
Defined Benefit Pension Plan | International
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain	1.9	0.0
Decrease in projected benefit obligation	9.1
Decrease in accumulated other comprehensive loss	9.1
Defined Benefit Pension Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year	25.0
Defined Benefit Pension Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year	35.0
Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Amortization of actuarial gain	$ 0.6	$ 0.4