Consolidated Statements Of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income
Balance (in shares) at Jul. 31, 2012		12,162,724
Balance at Jul. 31, 2012	$ 446,319	$ 608	$ 100,222	$ 343,186	$ 2,303
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, net of shares traded for taxes (in shares)		104,761
Stock grants and vesting of restricted stock units, net of shares traded for taxes	(3,121)	$ 5	(3,126)
Stock purchase plan (in shares)		7,488
Stock purchase plan	431		431
Share-based compensation expense	11,601		11,601
Tax benefit from share-based compensation	1,919		1,919
Repurchase of common stock (in shares)		(111,816)
Repurchase of common stock	(7,945)	$ (5)	(921)	(7,019)
Dividends declared ($0.40 per share)	(5,033)			(5,033)
Net income for the year	31,121			31,121
Other comprehensive income, net of tax	6,845				6,845
Balance (in shares) at Jul. 31, 2013		12,235,416
Balance at Jul. 31, 2013	486,396	$ 612	114,381	362,255	9,148
Shares issued for:
Stock options exercised (in shares)		81,538
Stock options exercised	4,885	$ 4	4,881
Stock grants and vesting of restricted stock units, net of shares traded for taxes (in shares)		233,799
Stock grants and vesting of restricted stock units, net of shares traded for taxes	(7,622)	$ 12	(7,634)
Stock purchase plan (in shares)		7,283
Stock purchase plan	491		491
Share-based compensation expense	11,457		11,457
Tax benefit from share-based compensation	3,824		3,824
Repurchase of common stock (in shares)		(185,044)
Repurchase of common stock	(14,959)	$ (9)	(1,721)	(13,229)
Dividends declared ($0.40 per share)	(5,029)			(5,029)
Net income for the year	34,480			34,480
Other comprehensive income, net of tax	$ (1,343)				(1,343)
Balance (in shares) at Jul. 31, 2014	12,372,992	12,372,992
Balance at Jul. 31, 2014	$ 512,580	$ 619	125,679	378,477	7,805
Shares issued for:
Stock options exercised (in shares)		135,444
Stock options exercised	7,274	$ 7	7,267
Stock grants and vesting of restricted stock units, net of shares traded for taxes (in shares)		92,743
Stock grants and vesting of restricted stock units, net of shares traded for taxes	(2,830)	$ 5	(2,835)
Stock purchase plan (in shares)		9,449
Stock purchase plan	617	$ (1)	618
Share-based compensation expense	10,836		10,836
Tax benefit from share-based compensation	764		764
Repurchase of common stock (in shares)		(176,611)
Repurchase of common stock	(13,872)	$ (9)	(1,791)	(12,072)
Dividends declared ($0.40 per share)	(5,129)			(5,129)
Net income for the year	33,481			33,481
Other comprehensive income, net of tax	$ (12,311)				(12,311)
Balance (in shares) at Jul. 31, 2015	12,434,017	12,434,017
Balance at Jul. 31, 2015	$ 531,410	$ 621	$ 140,538	$ 394,757	$ (4,506)