Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Quarterly Financial Data [Abstract]
Net Sales	$ 610,578	$ 575,588	$ 588,537	$ 596,510	$ 668,226	$ 624,234	$ 581,622	$ 599,384	$ 2,371,213	$ 2,473,466	$ 2,436,948
Gross margin	202,344	194,100	203,088	209,052	238,323	223,461	201,648	214,394	808,584	877,826	847,127
Net earnings	$ 56,433	$ 47,776	$ 47,955	$ 55,947	$ 72,956	$ 67,336	$ 58,340	$ 61,592	$ 208,111	$ 260,224	$ 247,377
Basic earnings per share	$ 0.41	$ 0.35	$ 0.35	$ 0.40	$ 0.51	$ 0.46	$ 0.40	$ 0.42	$ 1.51	$ 1.79	$ 1.67
Diluted earnings per share	0.41	.34	0.34	0.40	0.50	0.46	0.39	0.41	$ 1.49	$ 1.76	$ 1.64
Dividends declared per share	.34		.33		0.165	0.165	0.140	0.140
Dividends paid per share	$ 0.170	$ 0.165	$ 0.165	$ 0.165	$ 0.165	$ 0.140	$ 0.140	$ 0.130