Condensed Consolidated Statements of Stockholders' Equity - USD ($)	Total	Common Stock	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Beginning balance at Jul. 31, 2015	$ 401,409,000	$ 3,117,000	$ 427,083,000	$ 413,058,000	$ (441,849,000)
Common stock, beginning balance (in shares) at Jul. 31, 2015		31,165,401
Treasury stock, beginning balance (in shares) at Jul. 31, 2015					15,033,317
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	3,125,000		3,125,000
Proceeds from issuance of employee stock purchase plan shares	499,000	$ 3,000	496,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		29,070
Common stock issued for net settlement of stock-based awards	(74,000)	$ 1,000	(75,000)
Common stock issued for net settlement of stock-based awards (in shares)		9,925
Cash dividends declared	(14,544,000)			(14,544,000)
Accrual of dividend equivalents, net of reversal	(97,000)			(97,000)
Net income tax shortfall from settlement of stock-based awards	(25,000)		(25,000)
Reversal of deferred tax assets associated with expired and unexercised stock-based awards	(55,000)		(55,000)
Net income (loss)	(10,440,000)			(10,440,000)
Ending balance at Apr. 30, 2016	379,798,000	$ 3,121,000	430,549,000	387,977,000	$ (441,849,000)
Common stock, ending balance (in shares) at Apr. 30, 2016		31,204,396
Treasury stock, ending balance (in shares) at Apr. 30, 2016					15,033,317
Beginning balance at Jul. 31, 2016	$ 470,401,000	$ 3,837,000	524,797,000	383,616,000	$ (441,849,000)
Common stock, beginning balance (in shares) at Jul. 31, 2016	38,367,997	38,367,997
Treasury stock, beginning balance (in shares) at Jul. 31, 2016	15,033,317				15,033,317
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	$ 2,980,000		2,980,000
Proceeds from issuance of employee stock purchase plan shares	514,000	$ 5,000	509,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		49,694
Issuance of restricted stock, net	0	$ 14,000	(14,000)
Issuance of restricted stock, net (in shares)		144,988
Common stock issued for net settlement of stock-based awards	(244,000)	$ 4,000	(248,000)
Common stock issued for net settlement of stock-based awards (in shares)		40,354
Cash dividends declared	(11,691,000)			(11,691,000)
Accrual of dividend equivalents, net of reversal	(228,000)			(228,000)
Net income tax shortfall from settlement of stock-based awards	(240,000)		(240,000)
Reversal of deferred tax assets associated with expired and unexercised stock-based awards	(350,000)		(350,000)
Net income (loss)	8,513,000			8,513,000
Ending balance at Apr. 30, 2017	$ 469,655,000	$ 3,860,000	$ 527,434,000	$ 380,210,000	$ (441,849,000)
Common stock, ending balance (in shares) at Apr. 30, 2017	38,603,033	38,603,033
Treasury stock, ending balance (in shares) at Apr. 30, 2017	15,033,317				15,033,317