Stock Option and Restricted Stock Awards Transactions (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Jul. 31, 2015	Jul. 31, 2014
Outstanding Stock Awards
Number of Shares
Outstanding at beginning period		381,790
Granted		78,846
Exercised		(135,444)
Vesting of restricted stock		0
Cancelled (forfeited and expired)		(38,894)
Outstanding at end period		286,298	381,790
Options vested or expected to vest at end period	[1]	279,074
Options exercisable at end period		126,873
Weighted Average Exercise Price
Outstanding at beginning period		$ 63.21
Granted		71.20
Exercised		53.70
Vesting of restricted stock		0
Cancelled (forfeited and expired)		73.72
Outstanding at end period		68.93	$ 63.21
Options vested or expected to vest at end period	[1]	68.82
Options exercisable at end period		$ 63.49
Weighted Average Remaining Contractual Term (Years)
Outstanding at end period		5 years 4 days	4 years 9 months
Options vested or expected to vest at end period	[1]	4 years 11 months 23 days
Options exercisable at end period		4 years 4 months 24 days
Aggregate Intrinsic Value
Outstanding at beginning period		$ 3,940
Outstanding at end period		3,332	$ 3,940
Options vested or expected to vest at end period	[1]	3,282
Options exercisable at end period		$ 2,167
Time Based Restricted Stock
Number of Shares/Units
Outstanding at beginning period		143,357
Granted		61,882
Exercised		0
Vesting of restricted stock		(62,195)
Cancelled (forfeited and expired)		(14,982)
Outstanding at end period		128,062	143,357
Weighted Average Grant Date Fair Value
Outstanding at beginning period		$ 74.25
Granted		73.23
Exercised		0
Vesting of restricted stock		71.12
Cancelled (forfeited and expired)		74.76
Outstanding at end period		$ 74.06	$ 74.25
Performance awards
Number of Shares/Units
Outstanding at beginning period	[2]	187,930
Granted	[2]	68,689
Exercised	[2]	0
Vesting of restricted stock	[2]	(68,151)
Cancelled (forfeited and expired)	[2]	(29,521)
Outstanding at end period	[2]	158,947	187,930
Weighted Average Grant Date Fair Value
Outstanding at beginning period		$ 85.25
Granted		79.59
Exercised		0
Vesting of restricted stock		80.46
Cancelled (forfeited and expired)		79.25
Outstanding at end period		$ 85.98	$ 85.25

[1] In addition to the vested options, we expect a portion of the unvested options to vest at some point in the future. Stock options expected to vest are calculated by applying an estimated forfeiture rate to the unvested options.

[2] The performance-based unvested restricted stock is shown in this table at target, except for the number of shares vested, which reflect the shares earned. As of July 31, 2015, the maximum number of performance-based unvested restricted stock available to be earned is 317,894.