Selected Quarterly Financial Data - Summary of Selected Quarterly Financial Data (Parenthetical) (Detail) (USD $)	3 Months Ended					12 Months Ended
	Jul. 31, 2013	Apr. 30, 2013	Jul. 31, 2012	Apr. 30, 2012	Oct. 31, 2011	Jul. 31, 2013	Jul. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Other operating gains (loss)		$ 9,600,000			$ (11,000,000)		$ (11,022,000)
Impairment of building and improvements	4,400,000					4,359,000
Estimated losses from pending litigation				(6,500,000)
Reversal of a portion of the valuation allowance on deferred income tax assets			$ 36,600,000