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
Beginning balance (in shares) at Jul. 31, 2013		12,235,416
Beginning 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 retained for taxes (in shares)		233,799
Stock grants and vesting of restricted stock units, net of shares retained 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)
Ending balance (in shares) at Jul. 31, 2014		12,372,992
Ending 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 retained for taxes (in shares)		92,743
Stock grants and vesting of restricted stock units, net of shares retained 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)
Ending balance (in shares) at Jul. 31, 2015	12,434,017	12,434,017
Ending balance at Jul. 31, 2015	$ 531,410	$ 621	140,538	394,757	(4,506)
Shares issued for:
Stock options exercised (in shares)		61,384
Stock options exercised	4,174	$ 3	4,171
Stock grants and vesting of restricted stock units, net of shares retained for taxes (in shares)		65,087
Stock grants and vesting of restricted stock units, net of shares retained for taxes	(2,724)	$ 3	(2,727)
Stock purchase plan (in shares)		8,176
Stock purchase plan	550	$ 1	549
Share-based compensation expense	8,739		8,739
Tax deficiency from share-based compensation	(324)		(324)
Repurchase of common stock (in shares)		(171,899)
Repurchase of common stock	(13,698)	$ (9)	(1,941)	(11,748)
Dividends declared ($0.40 per share)	(5,123)			(5,123)
Net income for the year	12,127			12,127
Other comprehensive income, net of tax	$ (3,954)				(3,954)
Ending balance (in shares) at Jul. 31, 2016	12,396,765	12,396,765
Ending balance at Jul. 31, 2016	$ 531,177	$ 619	$ 149,005	$ 390,013	$ (8,460)