Goodwill (Schedule of Accumulated Impairment Losses) (Details) - USD ($) $ in Millions		Jun. 30, 2018	Sep. 30, 2017
Goodwill [Line Items]
Goodwill, gross		$ 1,201.8	$ 1,138.7
Goodwill, net		794.1	721.5
Industrial Gases - Americas
Goodwill [Line Items]
Goodwill, accumulated impairment losses	[1]	(407.7)	(417.2)
Goodwill, net		$ 162.3	$ 163.7

[1] Accumulated impairment losses are attributable to our Latin America reporting unit (LASA) within the Industrial Gases – Americas segment and include impairment charges recorded in previous years as well as the impacts of currency translation on the losses.