Stockholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				1 Months Ended	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013 Regular Dividend	Oct. 31, 2013 Special Dividend	Nov. 19, 2013 Special Dividend Subsequent Event	Oct. 31, 2013 Restricted Stock Units (RSUs)	Oct. 31, 2012 Restricted Stock Units (RSUs)	Oct. 31, 2013 Restricted Stock Units (RSUs) Discontinued Operations	Oct. 31, 2012 Restricted Stock Units (RSUs) Discontinued Operations
Equity, Class of Treasury Stock [Line Items]
Total compensation expenses						$ 1,376	$ 669	$ 480	$ 52
Dividends declared and paid per common share	$ 0.23	$ 0.18	$ 0.23
Dividends declared and paid	12,253		12,253
Dividends declared per common share	$ 1.00			$ 1.00
Cash dividends	$ 12,253	$ 9,527			$ 53,290
Common stock, dividend record date				Nov. 05, 2013