Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Components of income before income taxes
United States									$ 512.1	$ 660.5	$ 607.3
Non-United States									431.0	467.0	526.9
Total	$ 236.9	$ 252.3	$ 217.0	$ 236.9	$ 278.9	$ 284.6	$ 276.5	$ 287.5	943.1	1,127.5	1,134.2
Current income tax provision:
United States									175.9	238.6	219.4
Non-United States									91.7	73.6	85.3
State and local									16.3	17.0	9.9
Total current									283.9	329.2	314.6
Deferred income tax provision:
United States									(53.7)	(30.3)	(3.8)
Non-United States									(8.8)	2.6	(4.0)
State and local									(8.0)	(1.6)	0.6
Total deferred									(70.5)	(29.3)	(7.2)
Income tax provision									213.4	299.9	307.4
Total income taxes paid									$ 299.8	$ 313.1	$ 323.8