Earnings per share (Schedule of Calculation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2023	Aug. 31, 2022	Aug. 31, 2023	Aug. 31, 2022
Earnings Per Share [Abstract]
Net income	$ 19,098	$ 21,797	$ 54,862	$ 71,361
Weighted average shares outstanding (in shares)	43,452	43,211	43,365	43,589
Basic earnings per common share (in dollars per share)	$ 0.44	$ 0.50	$ 1.27	$ 1.64
Diluted earnings per common share:
Net income	$ 19,098	$ 21,797	$ 54,862	$ 71,361
Effect of dilution from common stock equivalents (in shares)	1,353	724	1,178	710
Effect of dilution from if-converted Convertible Senior Notes (in shares)	176	0	0	0
Diluted weighted average shares outstanding (in shares)	44,981	43,935	44,543	44,299
Diluted earnings per share (in dollars shares)	$ 0.42	$ 0.50	$ 1.23	$ 1.61