Consolidated Comprehensive Income Statements (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 357.0	$ 161.7
Other Comprehensive Income (Loss), net of tax:
Translation adjustments, net of tax	(68.1)	136.4
Net gain (loss) on derivatives, net of tax	(10.3)	(9.5)
Pension and postretirement benefits, net of tax	(3.9)	0.0
Reclassification adjustments:
Currency translation adjustment	0.0	3.1
Derivatives, net of tax	(3.1)	0.8
Pension and postretirement benefits, net of tax	15.2	22.9
Total Other Comprehensive Income (Loss)	(70.2)	153.7
Comprehensive Income	286.8	315.4
Net Income Attributable to Noncontrolling Interests	9.5	7.1
Other Comprehensive Income (Loss) Attributable to Noncontrolling Interests	(0.9)	1.9
Comprehensive Income Attributable to Air Products	$ 278.2	$ 306.4