Earnings per share (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, 2019	Aug. 31, 2018		Aug. 31, 2019	Aug. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 13,557	$ 14,390	[1]	$ 31,140	$ 41,026	[1]
Weighted average shares outstanding (in shares)	44,716	45,130	[1]	44,761	45,730	[1]
Dilutive impact from common stock equivalents (in shares)	587	446		531	650
Diluted weighted average shares outstanding (in shares)	45,303	45,576	[1]	45,292	46,380	[1]
Basic earnings per share (in dollars per share)	$ 0.30	$ 0.32	[1]	$ 0.70	$ 0.90	[1]
Diluted earnings per share (in dollars per share)	$ 0.30	$ 0.32	[1]	$ 0.69	$ 0.88	[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.