Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock, at cost
Beginning Balance (in shares) at Jul. 31, 2015		41,604,359
Beginning Balance at Jul. 31, 2015	$ 406,633	$ 4,591	$ 156,050	$ 287,105	$ 1,224	$ (42,337)
Increase (Decrease) in Stockholders' Equity
Repurchases of shares (in shares)		(67,038)
Repurchases of shares	(3,732)					(3,732)
Stock-based compensation	8,361		8,361
Issuance of restricted stock (in shares)		175,700
Issuance of restricted stock	0	$ 17	(17)
Cancellations of restricted stock (in shares)		(4,807)
Cancellations of restricted stock	0
Excess tax benefit from exercises of stock options and vesting of restricted stock	1,179		1,179	0
Dividends on common stock	(5,005)			(5,005)
Net income	59,953			59,953
Other comprehensive income (loss)	(13,019)				(13,019)
Ending Balance (in shares) at Jul. 31, 2016		41,708,214
Ending Balance at Jul. 31, 2016	454,370	$ 4,608	165,573	342,053	(11,795)	(46,069)
Increase (Decrease) in Stockholders' Equity
Repurchases of shares (in shares)		(89,607)
Repurchases of shares	(6,910)					(6,910)
Stock-based compensation	8,844		8,844
Issuance of restricted stock (in shares)		116,506
Issuance of restricted stock	0	$ 12	(12)
Cancellations of restricted stock (in shares)		(6,179)
Cancellations of restricted stock	0	$ (1)	1
Excess tax benefit from exercises of stock options and vesting of restricted stock	196		196
Dividends on common stock	(5,841)			(5,841)
Net income	71,378			71,378
Other comprehensive income (loss)	$ 1,895				1,895
Ending Balance (in shares) at Jul. 31, 2017	41,728,934	41,728,934
Ending Balance at Jul. 31, 2017	$ 523,932	$ 4,619	174,602	407,590	(9,900)	(52,979)
Increase (Decrease) in Stockholders' Equity
Repurchases of shares (in shares)		(62,559)
Repurchases of shares	(7,074)					(7,074)
Stock-based compensation	9,615		9,615
Issuance of restricted stock (in shares)		46,551
Issuance of restricted stock	0	$ 5	(5)
Cancellations of restricted stock (in shares)		(6,842)
Cancellations of restricted stock	0
Dividends on common stock	(7,091)			(7,091)
Net income	91,041			91,041
Other comprehensive income (loss)	$ (1,556)				(1,556)
Ending Balance (in shares) at Jul. 31, 2018	41,706,084	41,706,084
Ending Balance at Jul. 31, 2018	$ 608,867	$ 4,624	$ 184,212	$ 491,540	$ (11,456)	$ (60,053)