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
Beginning balance (in shares) at Jul. 31, 2018			38,860,571
Beginning balance (in shares) at Jul. 31, 2018							15,033,317
Beginning balance at Jul. 31, 2018	$ 505,684,000		$ 3,886,000	$ 538,453,000	$ 405,194,000		$ (441,849,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity-classified stock award compensation	$ 11,427,000			11,427,000
Proceeds from exercises of stock options (in shares)	80,930		8,100
Proceeds from exercises of stock options	$ 216,000		$ 1,000	215,000
Proceeds from issuance of employee stock purchase plan shares (in shares)			43,316
Proceeds from issuance of employee stock purchase plan shares	926,000		$ 4,000	922,000
Issuance of restricted stock (in shares)			10,386
Issuance of restricted stock	0		$ 1,000	(1,000)
Net settlement of stock-based awards (in shares)			145,119
Net settlement of stock-based awards	(3,916,000)		$ 15,000	(3,931,000)
Common stock issued for acquisitions (in shares)			208,669
Common stock issued for acquisitions	5,606,000		$ 21,000	5,585,000
Cash dividends declared, net	(9,575,000)				(9,575,000)
Accrual of dividend equivalents, net of reversal	(327,000)				(327,000)
Net (loss) income	25,041,000				25,041,000
Ending balance (in shares) at Jul. 31, 2019			39,276,161
Ending balance (in shares) at Jul. 31, 2019							15,033,317
Ending 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	$ 9,275,000			9,275,000
Proceeds from exercises of stock options (in shares)	285,790		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)			52,958
Proceeds from issuance of employee stock purchase plan shares	855,000		$ 5,000	850,000
Issuance of restricted stock, net of forfeiture (in shares)			3,319
Issuance of restricted stock, net of forfeiture	0
Net settlement of stock-based awards (in shares)			251,797
Net settlement of stock-based awards	(4,888,000)		$ 25,000	(4,913,000)
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	(9,794,000)				(9,794,000)
Accrual of dividend equivalents, net of reversal	(294,000)				(294,000)
Net (loss) income	$ 7,020,000				7,020,000
Ending balance (in shares) at Jul. 31, 2020	39,924,439		39,924,439
Ending balance (in shares) at Jul. 31, 2020	15,033,317						15,033,317
Ending 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]
Accounting Standards Update [Extensible List]		Accounting Standards Update 2016-13 [Member]
Equity-classified stock award compensation	9,983,000			9,983,000
Proceeds from issuance of employee stock purchase plan shares (in shares)			54,762
Proceeds from issuance of employee stock purchase plan shares	809,000		$ 5,000	804,000
Issuance of restricted stock, net of forfeiture (in shares)			35,495
Issuance of restricted stock, net of forfeiture	0		$ 4,000	(4,000)
Net settlement of stock-based awards (in shares)			240,549
Net settlement of stock-based awards	(4,000,000)		$ 24,000	(4,024,000)
Common stock issued for acquisitions (in shares)			1,026,567
Common stock issued for acquisitions	28,892,000		$ 103,000	28,789,000
Cash dividends declared, net	(10,189,000)				(10,189,000)
Accrual of dividend equivalents, net of reversal	(380,000)				(380,000)
Net (loss) income	$ (73,480,000)				(73,480,000)
Ending balance (in shares) at Jul. 31, 2021	41,281,812		41,281,812
Ending balance (in shares) at Jul. 31, 2021	15,033,317						15,033,317
Ending balance at Jul. 31, 2021	$ 500,719,000		$ 4,128,000	$ 605,439,000	$ 333,001,000		$ (441,849,000)