Business Segment Information (Reconciliation of Operating Income) (Details) - USD ($) $ in Millions	3 Months Ended		4 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015
Segment Reporting Information [Line Items]
Business separation costs	$ (12.0)	$ 0.0	$ (19.5)
Project suspension costs	(14.3)	0.0
Business restructuring and cost reduction actions	0.0	(32.4)
Gain on previously held equity interest	0.0	17.9
Operating Income	493.0	430.0
Segment Total [Member]
Segment Reporting Information [Line Items]
Operating Income	519.3	444.5
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Business separation costs	(12.0)	0.0
Business restructuring and cost reduction actions	0.0	(32.4)
Gain on previously held equity interest	$ 0.0	$ 17.9