Earnings Per Common Share - Computation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Numerator for basic and diluted earnings per share:
Net income	$ 24,464	$ 5,767
Less income allocated to participating securities	0	(2)
Net income available to common shareholders	$ 24,464	$ 5,765
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)	42,184,486	42,022,383
Dilutive effect of stock awards using the treasury stock method and the average market price for the year (in shares)	154,352	146,422
Dilutive effect of convertible debt outstanding (in shares)	619,640	0
Denominator for diluted earnings per share - weighted average number of shares and common stock equivalents attributable to common stock (in shares)	42,958,478	42,168,805
Earnings per share attributable to common stock:
Basic earnings per share (in dollars per share)	$ 0.58	$ 0.14
Diluted earnings per share (in dollars per share)	$ 0.57	$ 0.14
Stock awards excluded because their inclusion would have been anti-dilutive (in shares)	0	0