Goodwill (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Sep. 30, 2017
Goodwill [Line Items]
Goodwill, accumulated impairment losses	$ 433.6	$ 417.2
Industrial Gases - Americas
Goodwill [Line Items]
Goodwill, accumulated impairment losses	$ 433.6

Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a,h)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Name:	us-gaap_GoodwillImpairedAccumulatedImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant