Fair Value of Option Grant Assumptions (Parenthetical) (Detail) (Total Shareholders Return)	12 Months Ended
	Jul. 31, 2014		Jul. 31, 2013		Jul. 31, 2012
Total Shareholders Return
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]
Expected annual dividend yield	0.00%	[1]	0.00%	[1]	0.00%	[1]

[1] Dividends are considered reinvested when calculating TSR. The dividend yield is therefore considered to be 0%.