Consolidated Comprehensive Income Statements (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 433.5	$ 423.6	$ 790.5	$ 585.3
Other Comprehensive Income (Loss), net of tax:
Translation adjustments, net of tax	51.3	125.6	(16.8)	262.0
Net gain (loss) on derivatives, net of tax	(35.4)	17.8	(45.7)	8.3
Pension and postretirement benefits, net of tax			(3.9)	0.0
Reclassification adjustments:
Currency translation adjustment			0.0	3.1
Derivatives, net of tax	36.9	(7.5)	33.8	(6.7)
Pension and postretirement benefits, net of tax	18.7	26.6	33.9	49.5
Total Other Comprehensive Income	71.5	162.5	1.3	316.2
Comprehensive Income	505.0	586.1	791.8	901.5
Net Income Attributable to Noncontrolling Interests	12.2	7.2	21.7	14.3
Other Comprehensive Income Attributable to Noncontrolling Interests	5.1	2.2	4.2	4.1
Comprehensive Income Attributable to Air Products	$ 487.7	$ 576.7	$ 765.9	$ 883.1