Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Decrease in underfunded status of pension plan due to transfer to spin-off company	$ 24.0
Effect on accumulated other comprehensive loss related to transfer of defined benefit plan assets and obligations	5.0
Company contributions	24.9	$ 51.8	$ 79.3
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year	65.0
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year	85.0
Materials Technologies [Member]
Defined Benefit Plan Disclosure [Line Items]
Periodic benefit costs including settlement, curtailment, termination benefits, and other costs	$ 2.5