Amount of receivables arising from transactions with related parties due within one year or the normal operating cycle, if longer.

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Name:	us-gaap_AccountsReceivableRelatedPartiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Supplemental Information (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2020
Related Party Transaction [Line Items]
Trade receivables, net	$ 105.0		$ 95.0
Related party debt, including current portion	355.5
Equity affiliate and joint venture partner
Related Party Transaction [Line Items]
Sales to and other income from related parties	$ 50.0	$ 90.0
Air Products Lu'an Changzhi Co Ltd [Member]
Related Party Transaction [Line Items]
Related party debt, including current portion			$ 338.5