Earnings per share - Calculation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Feb. 28, 2022	Feb. 28, 2021
Earnings Per Share [Abstract]
Net income	$ 20,454	$ 18,961
Weighted average shares outstanding (in shares)	43,981	44,108
Basic earnings per common share (in dollars per share)	$ 0.47	$ 0.43
Diluted earnings per common share:
Net income	$ 20,454	$ 18,961
Effect of dilution from common stock equivalents (in shares)	727	544
Diluted weighted average shares outstanding (in shares)	44,708	44,652
Diluted earnings per share (in dollars shares)	$ 0.46	$ 0.42