Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Earnings Per Share [Abstract]
Options excluded from the diluted net earnings per share calculation (in shares)									3,164,159	977,824	884,138
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted average common shares – basic (in shares)									133,800,000	137,800,000	145,600,000
Diluted share equivalents (in shares)									1,000,000	1,600,000	2,000,000
Weighted average common shares – diluted (in shares)									134,800,000	139,400,000	147,600,000
Net earnings for basic and diluted earnings per share computation	$ 59.5	$ 54.8	$ 38.0	$ 38.5	$ 56.4	$ 47.8	$ 48.0	$ 55.9	$ 190.8	$ 208.1	$ 260.2
Net earnings per share:
Basic (in shares)	$ 0.44	$ 0.41	$ 0.28	$ 0.29	$ 0.41	$ 0.35	$ 0.35	$ 0.40	$ 1.43	$ 1.51	$ 1.79
Diluted (in shares)	$ 0.44	$ 0.41	$ 0.28	$ 0.29	$ 0.41	$ 0.34	$ 0.34	$ 0.40	$ 1.42	$ 1.49	$ 1.76