Stockholders' Equity - Stock Option Grants, Activity And Expense (Details) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended		9 Months Ended
	Aug. 31, 2019 USD ($) individual $ / shares shares	May 31, 2019	Aug. 31, 2018 USD ($) $ / shares shares	May 31, 2018	May 31, 2019 $ / shares shares	May 31, 2018 $ / shares shares	Aug. 31, 2019 USD ($) individual $ / shares shares	Aug. 31, 2018 USD ($) $ / shares shares
Other Disclosures
Number of option holders | individual	26						26
Unrecognized compensation expense related to non-vested stock options that will be recognized during future periods
Balance of Fiscal 2019 | $	$ 57						$ 57
Fiscal 2020 | $	149						149
Fiscal 2021 | $	$ 39						$ 39
2009 Stock Option Plan
2009 Stock Option Plan
Expiration term							10 years
Number of options that may be exercised as stock appreciation rights	0						0
Granted (in shares)							5,946	5,195
Assumptions used in determining the fair value of the stock options granted
Expected volatility (as a percent)							30.90%	30.50%
Risk free interest rates (as a percent)							2.30%	3.00%
Expected option term (in years)							8 years 6 months	8 years 6 months
Annual dividend yield (as a percent)							1.20%	1.10%
Compensation expense for stock options
Compensation expense (benefit) | $	$ 21		$ 83				$ 205	$ 261
Related tax benefit (expense) | $	$ 9		$ 14				$ 35	$ 40
Activity under the 2009 Stock Option Plan
Outstanding at beginning of period (in shares)					224,001	333,762	224,001	333,762
Granted (in shares)							5,946	5,195
Exercised (in shares)							(29,838)	(74,554)
Forfeited (in shares)							(7,788)	(20,279)
Outstanding at end of period (in shares)	192,321		244,124				192,321	244,124
Weighted Avg. Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares					$ 28.20	$ 29.22	$ 28.20	$ 29.22
Granted (in dollars per share) | $ / shares							36.99	38.48
Exercised (in dollars per share) | $ / shares							28.71	31.97
Forfeited (in dollars per share) | $ / shares							32.62	33.78
Outstanding at end of period (in dollars per share) | $ / shares	$ 28.21		$ 28.20				$ 28.21	$ 28.20
2009 Stock Option Plan | Non-employee directors
2009 Stock Option Plan
Granted (in shares)							5,946	5,195
Fair values of stock options granted (in dollars per share) | $ / shares							$ 12.87	$ 14.41
Activity under the 2009 Stock Option Plan
Granted (in shares)							5,946	5,195
2009 Stock Option Plan | Minimum
Compensation expense for stock options
Forfeiture rates (as a percent)	0.00%		0.00%				0.00%	0.00%
2009 Stock Option Plan | Minimum | Executives
Compensation expense for stock options
Forfeiture rates (as a percent)			17.90%					17.90%
2009 Stock Option Plan | Minimum | Employee
Compensation expense for stock options
Forfeiture rates (as a percent)	38.30%	38.30%		38.30%	38.30%	38.30%	38.30%
2009 Stock Option Plan | Maximum
Compensation expense for stock options
Forfeiture rates (as a percent)	2.00%		2.00%				2.00%	2.00%