Stock Option and RSU Transactions (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Jul. 31, 2017	Jul. 31, 2016
Outstanding Stock Awards
Number of Shares
Outstanding at beginning period		217,905
Granted		0	0
Exercised		(119,661)
Cancelled (forfeited and expired)		(26,395)
Outstanding at end period		71,849	217,905
Options vested or expected to vest at end period	[1]	71,779
Options exercisable at end period		64,604
Weighted Average Exercise Price
Outstanding at beginning period		$ 69.06
Exercised		69.52
Cancelled (forfeited and expired)		72.90
Outstanding at end period		66.87	$ 69.06
Options vested or expected to vest at end period	[1]	66.86
Options exercisable at end period		$ 66.40
Weighted Average Remaining Contractual Term (Years)
Outstanding at end period		3 years 1 month 16 days	4 years 1 month 24 days
Options vested or expected to vest at end period	[1]	3 years 1 month 16 days
Options exercisable at end period		3 years 7 days
Aggregate Intrinsic Value
Outstanding at beginning period		$ 3,265
Outstanding at end period		480	$ 3,265
Options vested or expected to vest at end period	[1]	480
Options exercisable at end period		$ 480
Time Based Restricted Stock
Number of Shares/Units
Outstanding at beginning period		133,560
Granted		92,613
Vesting of restricted stock		(72,246)
Cancelled (forfeited and expired)		(56,486)
Outstanding at end period		97,441	133,560
Weighted Average Grant Date Fair Value
Outstanding at beginning period		$ 78.98
Granted		88.13
Vesting of restricted stock		75.69
Cancelled (forfeited and expired)		85.88
Outstanding at end period		$ 86.11	$ 78.98
Performance awards
Number of Shares/Units
Outstanding at beginning period	[2]	167,114
Granted	[2]	93,260
Vesting of restricted stock	[2]	(24,205)
Cancelled (forfeited and expired)	[2]	(40,650)
Outstanding at end period	[2]	195,519	167,114
Weighted Average Grant Date Fair Value
Outstanding at beginning period		$ 90.33
Granted		87.46
Vesting of restricted stock		115.59
Cancelled (forfeited and expired)		80.55
Outstanding at end period		$ 87.86	$ 90.33

[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 RSU’s are shown in this table at target, except for the number of shares vested, which reflect the shares earned. As of July 31, 2017, the maximum number of performance-based unvested RSU’s available to be earned is 343,020.