Condensed Consolidated Statements of Stockholders' Equity (USD $)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Beginning balance at Jul. 31, 2011	$ 629,180,000	$ 2,873,000	$ 355,001,000	$ 393,109,000	$ (121,803,000)
Treasury stock shares outstanding, beginning of period (in shares) at Jul. 31, 2011					4,508,445
Common stock shares issued, beginning of period (in shares) at Jul. 31, 2011		28,731,265
Equity-classified stock award compensation	1,834,000		1,834,000
Proceeds from exercise of options or units (in shares)		114,160
Proceeds from exercise of options	2,587,000	12,000	2,575,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		23,664
Proceeds from issuance of employee stock purchase plan shares	556,000	2,000	554,000
Cash dividends declared	(11,454,000)			(11,454,000)
Net excess income tax benefit (income tax shortfall) from stock-based award exercises	(81,000)		(81,000)
Reversal of deferred tax assets associated with expired and unexercised stock-based awards	(1,186,000)		(1,186,000)
Repurchases of common stock (in shares)	5,066,292				5,066,292
Repurchases of common stock	(155,744,000)				(155,744,000)
Net income	18,422,000			18,422,000
Ending balance at Jan. 31, 2012	484,114,000	2,887,000	358,697,000	400,077,000	(277,547,000)
Common stock shares issued, end of period (in shares) at Jan. 31, 2012		28,869,089
Treasury stock shares outstanding, end of period (in shares) at Jan. 31, 2012					9,574,737
Beginning balance at Jul. 31, 2012	429,401,000	2,893,000	361,458,000	404,227,000	(339,177,000)
Treasury stock shares outstanding, beginning of period (in shares) at Jul. 31, 2012	11,564,059				11,564,059
Common stock shares issued, beginning of period (in shares) at Jul. 31, 2012	28,931,679	28,931,679
Equity-classified stock award compensation	1,532,000		1,532,000
Proceeds from exercise of options or units (in shares)		25,800
Proceeds from exercise of options	446,000	3,000	443,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		21,222
Proceeds from issuance of employee stock purchase plan shares	478,000	2,000	476,000
Cash dividends declared	(9,562,000)			(9,562,000)
Net excess income tax benefit (income tax shortfall) from stock-based award exercises	14,000		14,000
Reversal of deferred tax assets associated with expired and unexercised stock-based awards	(2,955,000)		(2,955,000)
Repurchases of common stock (in shares)	397,798				397,798
Repurchases of common stock	(10,477,000)				(10,477,000)
Net income	9,800,000			9,800,000
Ending balance at Jan. 31, 2013	$ 418,677,000	$ 2,898,000	$ 360,968,000	$ 404,465,000	$ (349,654,000)
Common stock shares issued, end of period (in shares) at Jan. 31, 2013	28,978,701	28,978,701
Treasury stock shares outstanding, end of period (in shares) at Jan. 31, 2013	11,961,857				11,961,857