Consolidated Statements Of Changes In Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income
Balance at Jul. 31, 2010	$ 409,042	$ 645	$ 77,085	$ 326,590	$ 4,722
Balance (in shares) at Jul. 31, 2010		12,884,708
Shares issued for:
Stock options exercised (in shares)		26,173
Stock options exercised	1,122	1	1,121
Stock grants and vesting of restricted stock units (in shares)		14,079
Stock grants and vesting of restricted stock units	393	1	392
Restricted stock cancellations and shares traded for taxes (in shares)		(98,585)
Restricted stock cancellations and shares traded for taxes	(1,174)	(5)	(1,169)
Stock purchase plan (in shares)		8,921
Stock purchase plan	368		368
Tax benefit (provision) from/for share-based compensation	(184)		(184)
Share-based compensation expense	9,638		9,638
Repurchase of common stock (in shares)		(300,289)
Repurchase of common stock	(15,187)	(15)	(1,844)	(13,328)
Dividends paid ($0.40 per share)	(5,154)			(5,154)
Net income for the year	17,833			17,833
Other comprehensive income (loss), net of tax	6,775				6,775
Balance at Jul. 31, 2011	423,472	627	85,407	325,941	11,497
Balance (in shares) at Jul. 31, 2011		12,535,007
Shares issued for:
Stock options exercised (in shares)		35,922
Stock options exercised	1,626	2	1,624
Stock grants and vesting of restricted stock units (in shares)		53,094
Stock grants and vesting of restricted stock units	2,477	2	2,475
Restricted stock cancellations and shares traded for taxes (in shares)		(45,075)
Restricted stock cancellations and shares traded for taxes	(473)	(2)	(471)
Stock purchase plan (in shares)		7,757
Stock purchase plan	375		375
Tax benefit (provision) from/for share-based compensation	67		67
Share-based compensation expense	13,396		13,396
Repurchase of common stock (in shares)		(423,981)
Repurchase of common stock	(23,260)	(21)	(2,651)	(20,588)
Dividends paid ($0.40 per share)	(5,238)			(5,238)
Net income for the year	43,071			43,071
Other comprehensive income (loss), net of tax	(9,194)				(9,194)
Balance at Jul. 31, 2012	446,319	608	100,222	343,186	2,303
Balance (in shares) at Jul. 31, 2012	12,162,724	12,162,724
Shares issued for:
Stock options exercised (in shares)		72,259
Stock options exercised	4,259	4	4,255
Stock grants and vesting of restricted stock units (in shares)		228,979
Stock grants and vesting of restricted stock units	1,556	11	1,545
Restricted stock cancellations and shares traded for taxes (in shares)		(124,218)
Restricted stock cancellations and shares traded for taxes	(4,677)	(6)	(4,671)
Stock purchase plan (in shares)		7,488
Stock purchase plan	431		431
Tax benefit (provision) from/for share-based compensation	1,919		1,919
Share-based compensation expense	11,601		11,601
Repurchase of common stock (in shares)		(111,816)
Repurchase of common stock	(7,945)	(5)	(921)	(7,019)
Dividends paid ($0.40 per share)	(5,033)			(5,033)
Net income for the year	31,121			31,121
Other comprehensive income (loss), net of tax	6,845				6,845
Balance at Jul. 31, 2013	$ 486,396	$ 612	$ 114,381	$ 362,255	$ 9,148
Balance (in shares) at Jul. 31, 2013	12,235,416	12,235,416