Condensed Consolidated Statements of Stockholders' Equity - USD ($)	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Convertible preferred stock issuance costs	$ 0
Establishment of initial convertible preferred stock purchase option liability	0
Dividend on convertible preferred stock	0
Beginning balance (in shares) at Jul. 31, 2020			39,924,439
Beginning balance (in shares) at Jul. 31, 2020							15,033,317
Beginning balance at Jul. 31, 2020	549,299,000	$ (215,000)	$ 3,992,000	$ 569,891,000	$ 417,265,000	$ (215,000)	$ (441,849,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	699,000			699,000
Proceeds from issuance of employee stock purchase plan shares (in shares)			15,265
Proceeds from issuance of employee stock purchase plan shares	182,000		$ 1,000	181,000
Issuance of restricted stock (in shares)			35,975
Issuance of restricted stock	0		$ 4,000	(4,000)
Net settlement of stock-based awards (in shares)			68,074
Net settlement of stock-based awards	(1,338,000)		$ 7,000	(1,345,000)
Cash dividends declared, net	(2,493,000)				(2,493,000)
Accrual of dividend equivalents, net of reversal	(142,000)				(142,000)
Net loss	(85,840,000)				(85,840,000)
Ending balance (in shares) at Oct. 31, 2020			40,043,753
Ending balance (in shares) at Oct. 31, 2020							15,033,317
Ending balance at Oct. 31, 2020	$ 460,152,000		$ 4,004,000	569,422,000	328,575,000		$ (441,849,000)
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred stock (in shares)	100,000
Issuance of convertible preferred stock	$ 100,000,000
Convertible preferred stock issuance costs	(4,007,000)
Establishment of initial convertible preferred stock purchase option liability	(1,005,000)
Dividend on convertible preferred stock	(235,000)
Adjustment to reflect redemption value of convertible preferred stock (including accrued dividends)	$ 5,247,000
Ending Balance (in shares) at Oct. 31, 2021	100,000
Ending Balance at Oct. 31, 2021	$ 100,235,000
Beginning balance (in shares) at Jul. 31, 2021	41,281,812		41,281,812
Beginning balance (in shares) at Jul. 31, 2021	15,033,317						15,033,317
Beginning balance at Jul. 31, 2021	$ 500,719,000		$ 4,128,000	605,439,000	333,001,000		$ (441,849,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	921,000			921,000
Proceeds from issuance of employee stock purchase plan shares (in shares)			10,540
Proceeds from issuance of employee stock purchase plan shares	229,000		$ 1,000	228,000
Issuance of restricted stock (in shares)			13,428
Issuance of restricted stock	0		$ 1,000	(1,000)
Net settlement of stock-based awards (in shares)			74,461
Net settlement of stock-based awards	(2,127,000)		$ 8,000	(2,135,000)
Adjustment to reflect redemption value of convertible preferred stock (including accrued dividends)	(5,247,000)				(5,247,000)
Cash dividends declared, net	(2,629,000)				(2,629,000)
Accrual of dividend equivalents, net of reversal	(88,000)				(88,000)
Net loss	$ (5,984,000)				(5,984,000)
Ending balance (in shares) at Oct. 31, 2021	41,380,241		41,380,241
Ending balance (in shares) at Oct. 31, 2021	15,033,317						15,033,317
Ending balance at Oct. 31, 2021	$ 485,794,000		$ 4,138,000	$ 604,452,000	$ 319,053,000		$ (441,849,000)