Operating Results of Discontinued Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Apr. 30, 2011	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Discontinued Operations:
Net sales		$ 448,385	$ 444,862	$ 415,066
Operating income of discontinued operations		12,080	15,303	12,303
Gain on involuntary conversion				9,417
Impairment charges	1,430	11,525		1,430
Income tax benefit (expense)		631	(4,999)	(5,664)
Income from discontinued operations, net of taxes		$ 1,186	$ 10,304	$ 14,626