Earnings Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Earnings Per Share [Abstract]
Reduction in weighted average shares as a result of the repurchase of common shares (in shares)			0	0
Weighted average performance shares outstanding during the period that are excluded from EPS calculation	237,000	203,000	235,000	196,000
Numerator:
Net income (loss) for basic calculation	$ 4,205,000	$ 3,495,000	$ (81,635,000)	$ 9,883,000
Numerator for diluted calculation	$ 4,205,000	$ 3,495,000	$ (81,635,000)	$ 9,883,000
Denominator:
Denominator for basic calculation (in shares)	25,337,000	24,659,000	25,321,000	24,607,000
Effect of dilutive securities:
Stock-based awards (in shares)	83,000	399,000	0	297,000
Denominator for diluted calculation (in shares)	25,420,000	25,058,000	25,321,000	24,904,000
Stock-based Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive equity-classified stock-based awards not included in calculation of diluted earnings per share (in shares)	1,496,000		1,515,000	178,000