CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($)	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock, at Cost	Total
Balance at Jul. 31, 2013	$ 4,518,000	$ 134,853,000	$ 203,762,000	$ 10,977,000	$ (32,978,000)	$ 321,132,000
Balance (in shares) at Jul. 31, 2013	41,138,121
Increase (Decrease) in Stockholders' Equity
Exercises of options	$ 21,000	1,420,000			(807,000)	634,000
Exercises of options (in shares)	187,468
Repurchases of shares					(4,439,000)	(4,439,000)
Repurchases of shares (in shares)	(132,023)
Stock-based compensation		5,409,000				5,409,000
Issuance of restricted stock	$ 26,000	(26,000)
Issuance of restricted stock (in shares)	258,760
Cancellations of restricted stock	$ (1,000)	1,000
Cancellations of restricted stock (in shares)	(10,066)
Excess tax benefit from exercises of stock options and vesting of restricted stock		4,391,000				4,391,000
Dividends on common stock			(3,721,000)			(3,721,000)
Net income			43,265,000			43,265,000
Other comprehensive income (loss)				(1,425,000)		(1,425,000)
Balance at Jul. 31, 2014	$ 4,564,000	146,048,000	243,306,000	9,552,000	(38,224,000)	365,246,000
Balance (in shares) at Jul. 31, 2014	41,442,260
Increase (Decrease) in Stockholders' Equity
Exercises of options	$ 13,000	981,000			(386,000)	608,000
Exercises of options (in shares)	130,911
Repurchases of shares					(3,727,000)	(3,727,000)
Repurchases of shares (in shares)	(100,286)
Stock-based compensation		5,867,000				5,867,000
Issuance of restricted stock	$ 15,000	(15,000)
Issuance of restricted stock (in shares)	144,278
Cancellations of restricted stock	$ (1,000)	1,000
Cancellations of restricted stock (in shares)	(12,804)
Excess tax benefit from exercises of stock options and vesting of restricted stock		3,168,000				3,168,000
Dividends on common stock			(4,154,000)			(4,154,000)
Net income			47,953,000			47,953,000
Other comprehensive income (loss)				(8,328,000)		(8,328,000)
Balance at Jul. 31, 2015	$ 4,591,000	156,050,000	287,105,000	1,224,000	(42,337,000)	$ 406,633,000
Balance (in shares) at Jul. 31, 2015	41,604,359					41,604,359
Increase (Decrease) in Stockholders' Equity
Repurchases of shares					(3,732,000)	$ (3,732,000)
Repurchases of shares (in shares)	(67,038)
Stock-based compensation		8,361,000				8,361,000
Issuance of restricted stock	$ 17,000	(17,000)
Issuance of restricted stock (in shares)	175,700
Cancellations of restricted stock (in shares)	(4,807)
Excess tax benefit from exercises of stock options and vesting of restricted stock		1,179,000				1,179,000
Dividends on common stock			(5,005,000)			(5,005,000)
Net income			59,953,000			59,953,000
Other comprehensive income (loss)				(13,019,000)		(13,019,000)
Balance at Jul. 31, 2016	$ 4,608,000	$ 165,573,000	$ 342,053,000	$ (11,795,000)	$ (46,069,000)	$ 454,370,000
Balance (in shares) at Jul. 31, 2016	41,708,214					41,708,214