Earnings per share (Calculation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			6 Months Ended
	May 31, 2019	May 31, 2018		May 31, 2019	May 31, 2018
Earnings Per Share [Abstract]
Net income	$ 8,181	$ 12,904	[1]	$ 17,583	$ 26,637	[1]
Weighted average shares outstanding (in shares)	44,611	45,531	[1]	44,784	46,030	[1]
Dilutive impact from common stock equivalents (in shares)	676	556		503	751
Diluted weighted average shares outstanding (in shares)	45,287	46,087	[1]	45,287	46,781	[1]
Basic earnings per share (in dollars per share)	$ 0.18	$ 0.28	[1]	$ 0.39	$ 0.58	[1]
Diluted earnings per share (in dollars per share)	$ 0.18	$ 0.28	[1]	$ 0.39	$ 0.57	[1]

[1] The Company adopted ASC 606 effective December 1, 2018 using the full retrospective method. See Note 1. Nature of Business and Basis of Presentation for further information.