Consolidated Comprehensive Income Statements (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 423.6	$ 2,135.7	$ 585.3	$ 2,442.1
Other Comprehensive Income (Loss), net of tax:
Translation adjustments, net of tax	125.6	149.6	262.0	(131.6)
Net gain (loss) on derivatives, net of tax	17.8	(15.4)	8.3	(25.2)
Pension and postretirement benefits, net of tax	0.0	3.8	0.0	3.8
Reclassification adjustments:
Currency translation adjustment	0.0	49.1	3.1	49.1
Derivatives, net of tax	(7.5)	5.8	(6.7)	31.4
Pension and postretirement benefits, net of tax	26.6	30.1	49.5	57.5
Total Other Comprehensive Income	162.5	223.0	316.2	(15.0)
Comprehensive Income	586.1	2,358.7	901.5	2,427.1
Net Income Attributable to Noncontrolling Interests	7.2	5.7	14.3	12.3
Other Comprehensive Income Attributable to Noncontrolling Interests	2.2	5.0	4.1	1.9
Comprehensive Income Attributable to Air Products	$ 576.7	$ 2,348.0	$ 883.1	$ 2,412.9