Quarterly Financial Information (Quarterly Financial Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Quarterly Financial Information [Abstract]
Net Sales	$ 668,226	$ 624,234	$ 581,622	$ 599,384	$ 632,594	$ 619,371	$ 596,036	$ 588,947	$ 2,473,466	$ 2,436,948	$ 2,493,248
Gross margin	238,323	223,461	201,648	214,394	228,356	221,501	198,977	198,293	877,826	847,127	873,763
Net earnings	$ 72,956	$ 67,336	$ 58,340	$ 61,592	$ 72,609	$ 69,842	$ 50,813	$ 54,113	$ 260,224	$ 247,377	$ 264,301
Basic earnings per share	$ 0.51	$ 0.46	$ 0.40	$ 0.42	$ 0.49	$ 0.47	$ 0.34	$ 0.36	$ 1.79	$ 1.67	$ 1.76
Diluted earnings per share	$ 0.50	$ 0.46	$ 0.39	$ 0.41	$ 0.48	$ 0.46	$ 0.34	$ 0.36	$ 1.76	$ 1.64	$ 1.73
Dividends declared per share	$ 0.165	$ 0.165	$ 0.140	$ 0.140	$ 0.130	$ 0.130	$ 0.100	$ 0.090	$ 0.61	$ 0.450	$ 0.335
Dividends paid per share	$ 0.165	$ 0.140	$ 0.140	$ 0.130	$ 0.130	$ 0.100	$ 0.090	$ 0.090