Consolidated Comprehensive Income Statements - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 1,809.4	$ 1,532.9	$ 3,021.2
Other Comprehensive Income (Loss), net of tax:
Translation adjustments, net of tax	(356.2)	(244.6)	101.9
Net gain (loss) on derivatives, net of tax	(44.1)	45.9	(12.6)
Pension and postretirement benefits, net of tax	(326.2)	179.4	251.6
Reclassification adjustments:
Currency translation adjustment	(2.6)	3.1	57.3
Derivatives, net of tax	12.3	(30.4)	24.2
Pension and postretirement benefits, net of tax	63.2	133.1	110.7
Total Other Comprehensive Income (Loss)	(653.6)	86.5	533.1
Comprehensive Income	1,155.8	1,619.4	3,554.3
Net Income Attributable to Noncontrolling Interests	49.4	35.1	20.8
Other Comprehensive Income (Loss) Attributable to Noncontrolling Interests	(19.9)	(19.0)	3.7
Comprehensive Income Attributable to Air Products	$ 1,126.3	$ 1,603.3	$ 3,529.8