Consolidated Comprehensive Income Statements (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 161.7	$ 306.4
Other Comprehensive Income (Loss), net of tax:
Translation adjustments, net of tax of ($6.6) and $32.3	136.4	(281.2)
Net loss on derivatives, net of tax of ($5.3) and ($10.7)	(9.5)	(9.8)
Reclassification adjustments:
Currency translation adjustment	3.1	0.0
Derivatives, net of tax of $1.7 and $10.6	0.8	25.6
Pension and postretirement benefits, net of tax of $11.0 and $12.9	22.9	27.4
Total Other Comprehensive Income (Loss)	153.7	(238.0)
Comprehensive Income	315.4	68.4
Net Income Attributable to Noncontrolling Interests	7.1	6.6
Other Comprehensive Income (Loss) Attributable to Noncontrolling Interests	1.9	(3.1)
Comprehensive Income Attributable to Air Products	$ 306.4	$ 64.9