Earnings Per Common Share - Computation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Oct. 31, 2019	Oct. 31, 2018
Numerator for basic and diluted earnings per share:
Net income	$ 5,767	$ 19,242
Less income allocated to participating securities	(2)	(33)
Net income available to common shareholders	$ 5,765	$ 19,209
Denominator for basic and diluted earnings per share, adjusted for participating securities:
Denominator for basic earnings per share - weighted average number of shares outstanding attributable to common stock (in shares)	42,022,383	41,640,745
Dilutive effect of stock awards using the treasury stock method and the average market price for the year (in shares)	146,422	65,028
Denominator for diluted earnings per share - weighted average number of shares and common stock equivalents attributable to common stock (in shares)	42,168,805	41,705,773
Earnings per share attributable to common stock:
Basic earnings per share (in dollars per share)	$ 0.14	$ 0.46
Diluted earnings per share (in dollars per share)	$ 0.14	$ 0.46
Stock options excluded from weighted average dilutive common shares outstanding because their inclusion would have been anti-dilutive (in shares)	0	0