Consolidated Comprehensive Income Statements (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 487.9	$ 104.1	$ 1,073.2	$ 2,546.2
Other Comprehensive Income (Loss), net of tax:
Translation adjustments, net of tax	(392.4)	141.4	(130.4)	9.8
Net gain (loss) on derivatives, net of tax	27.1	23.0	35.4	(2.2)
Pension and postretirement benefits, net of tax	0.0	0.1	0.0	3.9
Reclassification adjustments:
Currency translation adjustment	0.0	8.2	3.1	57.3
Derivatives, net of tax	(17.7)	(23.6)	(24.4)	7.8
Pension and postretirement benefits, net of tax	26.0	27.7	75.5	85.2
Total Other Comprehensive Income (Loss)	(357.0)	176.8	(40.8)	161.8
Comprehensive Income	130.9	280.9	1,032.4	2,708.0
Net Income Attributable to Noncontrolling Interests	14.0	2.2	28.3	14.5
Other Comprehensive Income (Loss) Attributable to Noncontrolling Interests	(14.5)	0.2	(10.4)	2.1
Comprehensive Income Attributable to Air Products	$ 131.4	$ 278.5	$ 1,014.5	$ 2,691.4