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, 2013	$ 404,062,000	$ 2,907,000	$ 363,888,000	$ 403,398,000	$ (366,131,000)
Treasury stock shares outstanding, beginning of period (in shares) at Jul. 31, 2013					12,608,501
Common stock shares issued, beginning of period (in shares) at Jul. 31, 2013		29,066,792
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	1,990,000		1,990,000
Equity-classified stock awards issued	139,000		139,000
Proceeds from exercise of options	2,559,000	10,000	2,549,000
Proceeds from exercise of options (in shares)		95,425
Proceeds from issuance of employee stock purchase plan shares	430,000	2,000	428,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		20,727
Common stock issued for net settlement of stock-based awards	(25,000)	0	(25,000)
Common stock issued for net settlement of stock-based awards (in shares)		3,496
Cash dividends declared	(9,260,000)			(9,260,000)
Accrual of dividend equivalents	(51,000)			(51,000)
Net income tax shortfall from settlement of stock-based awards	(155,000)		(155,000)
Reversal of deferred tax assets associated with expired and unexercised stock-based awards	(1,925,000)		(1,925,000)
Repurchases of common stock	(29,107,000)				(29,107,000)
Repurchases of common stock (in shares)	935,992				935,992
Net income	11,288,000			11,288,000
Ending balance at Jan. 31, 2014	379,945,000	2,919,000	366,889,000	405,375,000	(395,238,000)
Treasury stock shares outstanding, end of period (in shares) at Jan. 31, 2014					13,544,493
Common stock shares issued, end of period (in shares) at Jan. 31, 2014		29,186,440
Beginning balance at Jul. 31, 2014	396,925,000	3,102,000	421,240,000	409,443,000	(436,860,000)
Treasury stock shares outstanding, beginning of period (in shares) at Jul. 31, 2014	14,857,582				14,857,582
Common stock shares issued, beginning of period (in shares) at Jul. 31, 2014	31,016,469	31,016,469
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	2,398,000		2,398,000
Equity-classified stock awards issued	0
Proceeds from exercise of options	119,000	0	119,000
Proceeds from exercise of options (in shares)		4,200
Proceeds from issuance of employee stock purchase plan shares	479,000	2,000	477,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		16,491
Common stock issued for net settlement of stock-based awards	(389,000)	6,000	(395,000)
Common stock issued for net settlement of stock-based awards (in shares)		58,577
Cash dividends declared	(9,732,000)			(9,732,000)
Accrual of dividend equivalents	(113,000)			(113,000)
Net income tax shortfall from settlement of stock-based awards	(149,000)		(149,000)
Reversal of deferred tax assets associated with expired and unexercised stock-based awards	(12,000)		(12,000)
Repurchases of common stock (in shares)	0
Net income	12,810,000			12,810,000
Ending balance at Jan. 31, 2015	$ 402,336,000	$ 3,110,000	$ 423,678,000	$ 412,408,000	$ (436,860,000)
Treasury stock shares outstanding, end of period (in shares) at Jan. 31, 2015	14,857,582				14,857,582
Common stock shares issued, end of period (in shares) at Jan. 31, 2015	31,095,737	31,095,737