Business Separation (Narrative)(Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Business separation costs	$ 7.4	$ 0.0	$ 19.4	$ 0.0

Legal and other advisory fees related to the intended separation of a business.

No definition available.

Name:	apd_BusinessSeparationCosts
Namespace Prefix:	apd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration