Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Sep. 30, 2025
Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Company contributions	$ 5.1	$ 8.2	$ 29.9
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 loss (gain)	$ 0.7	$ (0.3)