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, 2021	Feb. 29, 2020
Earnings Per Share [Abstract]
Net income	$ 18,961	$ 21,116
Weighted average shares outstanding (in shares)	44,108	44,897
Dilutive impact from common stock equivalents (in shares)	544	618
Diluted weighted average shares outstanding (in shares)	44,652	45,515
Basic earnings per share (in dollars per share)	$ 0.43	$ 0.47
Diluted earnings per share (in dollars per share)	$ 0.42	$ 0.46