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, 2012	$ 429,401,000	$ 2,893,000	$ 361,458,000	$ 404,227,000	$ (339,177,000)
Common stock shares issued, beginning of period (in shares) at Jul. 31, 2012		28,931,679
Treasury stock shares outstanding, beginning of period (in shares) at Jul. 31, 2012					11,564,059
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	3,159,000		3,159,000
Equity-classified stock awards issued	0
Proceeds from exercise of options	1,182,000	$ 9,000	1,173,000
Proceeds from exercise of options (in shares)		90,883
Issuance of restricted stock	0	$ 0	0
Issuance of restricted stock (in shares)		2,076
Proceeds from issuance of employee stock purchase plan shares	908,000	$ 5,000	903,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		42,154
Common stock issued for net settlement of stock-based awards	0
Cash dividends declared	(18,637,000)			(18,637,000)
Net excess income tax benefit (income tax shortfall) from settlement of stock-based awards	258,000		258,000
Reversal of deferred tax assets associated with expired and unexercised stock-based awards	(3,063,000)		(3,063,000)
Repurchases of common stock	(26,954,000)				$ (26,954,000)
Repurchases of common stock (in shares)					1,044,442
Net income	17,808,000			17,808,000
Ending balance at Jul. 31, 2013	404,062,000	$ 2,907,000	363,888,000	403,398,000	$ (366,131,000)
Common stock shares issued, end of period (in shares) at Jul. 31, 2013		29,066,792
Treasury stock shares outstanding, end of period (in shares) at Jul. 31, 2013					12,608,501
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	4,242,000		4,242,000
Equity-classified stock awards issued	139,000		139,000
Proceeds from exercise of options	6,058,000	$ 26,000	6,032,000
Proceeds from exercise of options (in shares)		255,094
Proceeds from issuance of employee stock purchase plan shares	913,000	$ 4,000	909,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		38,571
Common stock issued for net settlement of stock-based awards	(1,151,000)	$ 8,000	(1,159,000)
Common stock issued for net settlement of stock-based awards (in shares)		85,108
Debt converted to shares of common stock	49,753,000	$ 157,000	49,596,000
Debt converted to shares of common stock (in shares)		1,570,904
Cash dividends declared	(18,993,000)			(18,993,000)
Accrual of dividend equivalents	(113,000)			(113,000)
Net excess income tax benefit (income tax shortfall) from settlement of stock-based awards	(466,000)		(466,000)
Reversal of deferred tax assets associated with expired and unexercised stock-based awards	(1,941,000)		(1,941,000)
Repurchases of common stock	$ (70,729,000)				$ (70,729,000)
Repurchases of common stock (in shares)	2,249,081				2,249,081
Net income	$ 25,151,000			25,151,000
Ending balance at Jul. 31, 2014	$ 396,925,000	$ 3,102,000	421,240,000	409,443,000	$ (436,860,000)
Common stock shares issued, end of period (in shares) at Jul. 31, 2014	31,016,469	31,016,469
Treasury stock shares outstanding, end of period (in shares) at Jul. 31, 2014	14,857,582				14,857,582
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	$ 4,387,000		4,387,000
Equity-classified stock awards issued	0
Proceeds from exercise of options	1,439,000	$ 5,000	1,434,000
Proceeds from exercise of options (in shares)		50,000
Proceeds from issuance of employee stock purchase plan shares	917,000	$ 3,000	914,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		34,310
Common stock issued for net settlement of stock-based awards	(473,000)	$ 7,000	(480,000)
Common stock issued for net settlement of stock-based awards (in shares)		64,622
Cash dividends declared	(19,406,000)			(19,406,000)
Accrual of dividend equivalents	(224,000)			(224,000)
Net excess income tax benefit (income tax shortfall) from settlement of stock-based awards	(341,000)		(341,000)
Reversal of deferred tax assets associated with debt converted to shares of common stock	(58,000)		(58,000)
Reversal of deferred tax assets associated with expired and unexercised stock-based awards	(13,000)		(13,000)
Repurchases of common stock	$ (4,989,000)				$ (4,989,000)
Repurchases of common stock (in shares)	175,735				175,735
Net income	$ 23,245,000			23,245,000
Ending balance at Jul. 31, 2015	$ 401,409,000	$ 3,117,000	$ 427,083,000	$ 413,058,000	$ (441,849,000)
Common stock shares issued, end of period (in shares) at Jul. 31, 2015	31,165,401	31,165,401
Treasury stock shares outstanding, end of period (in shares) at Jul. 31, 2015	15,033,317				15,033,317