Business Segment Information (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Sales	$ 2,121.9	$ 1,914.5	$ 5,984.5	$ 5,558.2
Operating income (loss)	252.6	394.6	971.9	1,138.7
Contracts Accounted for under Percentage of Completion [Member] | Industrial Gases - Global [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	15.0		27.0
Intersegment Eliminations [Member] | Industrial Gases - Global [Member]
Segment Reporting Information [Line Items]
Sales	$ 57.4	$ 63.0	$ 179.4	$ 174.2