Condensed Consolidated Statements of Stockholders' Equity - USD ($)	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock
Beginning balance (in shares) at Jul. 31, 2019		39,276,161
Beginning balance (in shares) at Jul. 31, 2019					15,033,317
Beginning balance at Jul. 31, 2019	$ 535,082,000	$ 3,928,000	$ 552,670,000	$ 420,333,000	$ (441,849,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	2,117,000		2,117,000
Proceeds from exercises of stock options (in shares)		16,700
Proceeds from exercises of stock options	468,000	$ 2,000	466,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		20,010
Proceeds from issuance of employee stock purchase plan shares	510,000	$ 2,000	508,000
Issuance of restricted stock (in shares)		8,858
Issuance of restricted stock	0	$ 1,000	(1,000)
Net settlement of stock-based awards (in shares)		107,326
Net settlement of stock-based awards	(3,459,000)	$ 10,000	(3,469,000)
Common stock issued for acquisitions (in shares)		323,504
Common stock issued for acquisitions	11,575,000	$ 32,000	11,543,000
Cash dividends declared, net ($0.10 per share)	(4,860,000)			(4,860,000)
Accrual of dividend equivalents, net of reversal ($0.10 per share)	(113,000)			(113,000)
Net (loss) income	9,883,000			9,883,000
Ending balance (in shares) at Jan. 31, 2020		39,752,559
Ending balance (in shares) at Jan. 31, 2020					15,033,317
Ending balance at Jan. 31, 2020	551,203,000	$ 3,975,000	563,834,000	425,243,000	$ (441,849,000)
Beginning balance (in shares) at Oct. 31, 2019		39,402,226
Beginning balance (in shares) at Oct. 31, 2019					15,033,317
Beginning balance at Oct. 31, 2019	537,644,000	$ 3,940,000	551,316,000	424,237,000	$ (441,849,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	1,238,000		1,238,000
Proceeds from exercises of stock options (in shares)		6,100
Proceeds from exercises of stock options	162,000	$ 1,000	161,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		9,875
Proceeds from issuance of employee stock purchase plan shares	264,000	$ 1,000	263,000
Forfeiture of restricted stock (in shares)		(12,652)
Forfeiture of restricted stock	0	$ (1,000)	1,000
Net settlement of stock-based awards (in shares)		23,506
Net settlement of stock-based awards	(686,000)	$ 2,000	(688,000)
Common stock issued for acquisitions (in shares)		323,504
Common stock issued for acquisitions	11,575,000	$ 32,000	11,543,000
Cash dividends declared, net ($0.10 per share)	(2,432,000)			(2,432,000)
Accrual of dividend equivalents, net of reversal ($0.10 per share)	(57,000)			(57,000)
Net (loss) income	3,495,000			3,495,000
Ending balance (in shares) at Jan. 31, 2020		39,752,559
Ending balance (in shares) at Jan. 31, 2020					15,033,317
Ending balance at Jan. 31, 2020	$ 551,203,000	$ 3,975,000	563,834,000	425,243,000	$ (441,849,000)
Beginning balance (in shares) at Jul. 31, 2020	39,924,439	39,924,439
Beginning balance (in shares) at Jul. 31, 2020	15,033,317				15,033,317
Beginning balance at Jul. 31, 2020	$ 549,299,000	$ 3,992,000	569,891,000	417,265,000	$ (441,849,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	1,986,000		1,986,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		31,122
Proceeds from issuance of employee stock purchase plan shares	369,000	$ 3,000	366,000
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)		68,441
Net settlement of stock-based awards	(1,341,000)	$ 7,000	(1,348,000)
Cash dividends declared, net ($0.10 per share)	(4,988,000)			(4,988,000)
Accrual of dividend equivalents, net of reversal ($0.10 per share)	(191,000)			(191,000)
Net (loss) income	$ (81,635,000)			(81,635,000)
Ending balance (in shares) at Jan. 31, 2021	40,059,977	40,059,977
Ending balance (in shares) at Jan. 31, 2021	15,033,317				15,033,317
Ending balance at Jan. 31, 2021	$ 463,284,000	$ 4,006,000	570,891,000	330,236,000	$ (441,849,000)
Beginning balance (in shares) at Oct. 31, 2020		40,043,753
Beginning balance (in shares) at Oct. 31, 2020					15,033,317
Beginning balance at Oct. 31, 2020	460,152,000	$ 4,004,000	569,422,000	328,575,000	$ (441,849,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	1,287,000		1,287,000
Proceeds from issuance of employee stock purchase plan shares (in shares)		15,857
Proceeds from issuance of employee stock purchase plan shares	187,000	$ 2,000	185,000
Net settlement of stock-based awards (in shares)		367
Net settlement of stock-based awards	(3,000)		(3,000)
Cash dividends declared, net ($0.10 per share)	(2,495,000)			(2,495,000)
Accrual of dividend equivalents, net of reversal ($0.10 per share)	(49,000)			(49,000)
Net (loss) income	$ 4,205,000			4,205,000
Ending balance (in shares) at Jan. 31, 2021	40,059,977	40,059,977
Ending balance (in shares) at Jan. 31, 2021	15,033,317				15,033,317
Ending balance at Jan. 31, 2021	$ 463,284,000	$ 4,006,000	$ 570,891,000	$ 330,236,000	$ (441,849,000)