Schedule of Change in Retained Earnings (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Retained Earnings Adjustments [Line Items]
Beginning Balance	$ 953,740
Net income	41,108	30,988
Dividends declared and paid	(12,253)
Dividends declared but not paid	(53,290)
Ending Balance	$ 929,305