Supplemental Financial Statement Information - Cash flow, etc. (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2019	May 31, 2018
Supplemental Cash Flow Information
Increase (decrease) in accounts payable and accrued liabilities related to additions to real estate assets			$ 2,777	$ 4,584
Interest paid
Interest payments	$ 1,600	$ 1,496	3,219	2,929
Net proceeds from insurance settlement			126
Income Taxes
Income Tax Expense (Benefit)	1,683	32	1,503	822
Current income tax expense			1,562
Income tax benefit from exercise of stock options			59	46
Pretax income	$ 7,502	$ 363	$ 6,736	$ (570)
Effective income tax rate (as a percent)			23.20%	23.30%
Impact of lower statutory rate applied to deferred tax assets and deferred tax liabilities resulted for the re-measurement of deferred tax assets and liabilities				$ 1,001
Offsetting the net charge for the re-measurement of Griffin’s deferred tax assets and liabilities is an income tax benefit				133
Tax benefit			$ 59	$ 46
2009 Stock Option Plan
Supplemental Cash Flow Information
Treasury shares	22,390	18,405	22,390	18,405
Treasury stock	$ 846	$ 721	$ 846	$ 721