Cost Reduction and Asset Actions (Narrative) (Details) $ in Millions	3 Months Ended			6 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2017 USD ($) position	Mar. 31, 2016 USD ($)	Sep. 30, 2016 USD ($) position
Restructuring and Related Cost [Abstract]
Cost reduction and asset actions	$ 10.3		$ 10.7	$ 60.3	$ 10.7
Asset Actions [Member] | Industrial Gases - EMEA [Member]
Restructuring and Related Cost [Abstract]
Cost reduction and asset actions		$ 45.7
Cost Reduction Actions [Member]
Restructuring and Related Cost [Abstract]
Cost reduction and asset actions				63.7		$ 34.5
Net expense cost reduction and asset actions				60.3
Favorable restructuring reserve settlement				3.4
Cost Reduction Actions [Member] | Asset Actions [Member]
Restructuring and Related Cost [Abstract]
Cost reduction and asset actions				45.7		0.0
Cost Reduction Actions [Member] | Severance And Other Benefits [Member]
Restructuring and Related Cost [Abstract]
Cost reduction and asset actions	$ 10.3		$ 10.7	$ 18.0	$ 10.7	$ 34.5
Number of positions eliminated | position				140		610