Computations for Basic and Diluted Earnings (Loss) Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Oct. 31, 2014	Oct. 31, 2013
Earnings Per Share [Abstract]
Net income (loss)	$ 7,694	$ (42,153)
Less: income allocated to participating securities	(83)	0
Income (loss) attributable to common shareholders - basic	7,611	(42,153)
Add: undistributed income attributable to participating securities	83	0
Less: undistributed income reallocated to participating securities	(82)	0
Income (loss) attributable to common shareholders - diluted	$ 7,612	$ (42,153)
Weighted average shares outstanding - basic	31,042	21,954
Dilutive shares - stock options, RSU's, PSU's	426	0
Weighted average shares outstanding - diluted	31,468	21,954
Basic (in dollars per share)	$ 0.25	$ (1.92)
Diluted (in dollars per share)	$ 0.24	$ (1.92)