Segment Information - Net Income Reconciliation (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Disclosure Segment Information Net Income Reconciliation [Abstract]
Total profit from reportable segments	$ 61,573	$ 70,093	$ 141,828	$ 152,926
Corporate and eliminations	(1,794)	(2,359)	(3,767)	(5,622)
Unallocated amounts:
Administrative costs	(35,518)	(29,244)	(65,926)	(59,724)
Restructuring charges	(4,031)	0	(4,031)	0
Impairment charge	0	(115,688)	0	(115,688)
Non-routine items	5,220	0	1,782	0
Investment and other income	897	812	1,294	610
Interest expense	(4,406)	(4,933)	(8,569)	(9,980)
Income (loss) before income taxes	21,941	(81,319)	62,611	(37,478)
Income tax expense (benefit)	(30,625)	(8,635)	(44,107)	(19,744)
Net (loss) income	$ (8,684)	$ (89,954)	$ 18,504	$ (57,222)