Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Quarterly Financial Data [Abstract]
Net sales	$ 724.7	$ 700.0	$ 664.7	$ 644.8	$ 660.1	$ 608.2	$ 550.6	$ 553.0	$ 2,734.2	$ 2,371.9	$ 2,220.3
Gross profit	252.7	239.6	218.9	224.3	229.5	211.5	187.9	194.2	935.5	823.1	754.8
Net earnings	$ 102.4	$ 69.9	$ (52.9)	$ 60.9	$ 68.2	$ 60.1	$ 46.5	$ 58.0	$ 180.3	$ 232.8	$ 190.8
Net earnings per share – basic (in dollars per share)	$ 0.79	$ 0.54	$ (0.40)	$ 0.47	$ 0.52	$ 0.45	$ 0.35	$ 0.43	$ 1.38	$ 1.76	$ 1.43
Net earnings per share – diluted (in dollars per share)	0.78	0.53	(0.40)	0.46	0.51	0.45	0.35	0.43	1.36	1.74	1.42
Dividends paid per share (in dollars per share)	$ 0.19	$ 0.18	$ 0.18	$ 0.18	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.730	$ 0.700	$ 0.685