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, 2020	May 31, 2019	May 31, 2020	May 31, 2019
Earnings Per Share [Abstract]
Net income	$ 16,968	$ 8,181	$ 38,084	$ 17,583
Weighted average shares outstanding (in shares)	44,889	44,611	44,893	44,784
Dilutive impact from common stock equivalents (in shares)	378	676	498	503
Diluted weighted average shares outstanding (in shares)	45,267	45,287	45,391	45,287
Basic earnings per share (in dollars per share)	$ 0.38	$ 0.18	$ 0.85	$ 0.39
Diluted earnings per share (in dollars per share)	$ 0.37	$ 0.18	$ 0.84	$ 0.39