Supplemental Financial Statement Information - Cash flow, etc. (Details) - USD ($) $ in Thousands				3 Months Ended
	Feb. 28, 2018	Jan. 01, 2018	Dec. 31, 2017	Feb. 28, 2018	Feb. 28, 2017
Supplemental Cash Flow Information
Increase (decrease) in value of available-for-sale securities: Investment in Centaur Media Plc					$ 195
Increase (decrease) in accounts payable and accrued liabilities related to additions to real estate assets				$ 47	82
Interest paid
Interest payments				1,433	1,232
Income Taxes
Corporate statutory income tax rate	22.00%	21.00%	35.00%
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				$ 211	$ 451
2009 Stock Option Plan
Supplemental Cash Flow Information
Treasury shares	5,000			5,000
Exercise of an option to acquire shares of common stock				5,471
Treasury stock	$ 186			$ 186