Equity (Changes in Equity) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 6 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2015
Mar. 31, 2014
Balance, beginning of period $ 7,503.3 $ 7,422.7 $ 7,521.4 $ 7,198.9
Net Income 296.9 290.8 629.0 588.6
Other comprehensive income (loss) (190.9) (71.2) (424.7) (18.6)
Cash Dividends (173.9) (163.4) (339.3) (313.7)
Dividends to noncontrolling interests (13.1) (5.6) (19.3) (10.2)
Share-based compensation 12.9 11.6 24.8 23.4
Issuance of treasury shares for stock option and award plans 32.8 34.7 62.9 47.9
Tax benefit of stock option and award plans 9.4 9.2 22.9 14.0
Purchase of noncontrolling interests 0 0 0 (0.5)
Other (1.1) (1.0) (1.4) (2.0)
Balance, end of period 7,476.3 7,527.8 7,476.3 7,527.8
Air Products Shareholders' Equity [Member]        
Balance, beginning of period 7,351.5 7,264.0 7,365.8 7,042.1
Net Income 290.0 283.5 614.6 573.7
Other comprehensive income (loss) (191.5) (67.7) (420.2) (14.0)
Cash Dividends (173.9) (163.4) (339.3) (313.7)
Dividends to noncontrolling interests 0 0 0 0
Share-based compensation 12.9 11.6 24.8 23.4
Issuance of treasury shares for stock option and award plans 32.8 34.7 62.9 47.9
Tax benefit of stock option and award plans 9.4 9.2 22.9 14.0
Purchase of noncontrolling interests 0 0 0 (0.5)
Other 1.3 (1.0) 1.0 (2.0)
Balance, end of period 7,332.5 7,370.9 7,332.5 7,370.9
Noncontrolling Interests [Member]        
Balance, beginning of period 151.8 158.7 155.6 156.8
Net Income 6.9 [1] 7.3 [1] 14.4 [1] 14.9 [1]
Other comprehensive income (loss) 0.6 (3.5) (4.5) (4.6)
Cash Dividends 0 0 0 0
Dividends to noncontrolling interests (13.1) (5.6) (19.3) (10.2)
Share-based compensation 0 0 0 0
Issuance of treasury shares for stock option and award plans 0 0 0 0
Tax benefit of stock option and award plans 0 0 0 0
Purchase of noncontrolling interests 0 0 0 0
Other (2.4) 0 (2.4) 0
Balance, end of period $ 143.8 $ 156.9 $ 143.8 $ 156.9
[1]
Net income attributable to noncontrolling interests excludes net income related to redeemable noncontrolling interests, which is not included in total equity. Refer to Note 15, Noncontrolling Interests, for additional information.