Supplemental Financial Statement Information - Cash flow, etc. (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 26, 2019	Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2019	Aug. 31, 2018	Nov. 30, 2017
Supplemental Cash Flow Information
Increase (decrease) in accounts payable and accrued liabilities related to additions to real estate assets				$ 1,483	$ 1,461
Interest paid
Interest payments		$ 1,609	$ 1,545	4,828	4,474
Net proceeds from insurance settlement				126
Income Taxes
Income Tax Expense (Benefit)		(814)	(89)	689	733
Current income tax expense				1,621
Pretax income		$ 203	$ (211)	$ 6,939	$ (781)
Effective income tax rate (as a percent)				23.40%	19.00%
Benefit arising from partial reduction of valuation allowance on deferred tax assets				$ 873
Income tax benefit from exercise of stock options				$ 59	$ 120
Capital based tax phasing period	4 years
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
Corporate statutory income tax rate					21.00%	35.00%
Offsetting the net charge for the re-measurement of Griffin’s deferred tax assets and liabilities is an income tax benefit					$ 148
2009 Stock Option Plan
Supplemental Cash Flow Information
Treasury shares		22,390	30,039	22,390	30,039
Treasury stock		$ 846	$ 1,189	$ 846	$ 1,189