Quarterly Financial Information (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Quarterly Financial Information (Unaudited)
Sales	$ 1,781.8	$ 1,649.5	$ 1,600.5	$ 1,591.7	$ 1,715.7	$ 1,624.2	$ 1,522.8	$ 1,489.2	$ 6,623.5	$ 6,351.9	$ 6,259.4
Gross profit	752.9	681.5	655.8	663.7	697.2	652.9	616.4	607.3	2,753.9	2,573.8	2,522.7
Income before income taxes	339.0	274.0	248.4	272.8	279.2	257.4	227.1	217.2	1,134.2	980.9	965.9
Net income	$ 248.7	$ 199.7	$ 180.3	$ 198.1	$ 215.3	$ 203.7	$ 175.9	$ 161.4	$ 826.8	$ 756.3	$ 737.0
Basic earnings per share:
Basic	$ 1.81	$ 1.44	$ 1.30	$ 1.43	$ 1.55	$ 1.46	$ 1.25	$ 1.16	$ 5.98	$ 5.43	$ 5.20
Diluted earnings per share:
Diluted	$ 1.79	$ 1.43	$ 1.28	$ 1.41	$ 1.53	$ 1.45	$ 1.24	$ 1.14	$ 5.91	$ 5.36	$ 5.13