Supplemental Financial Statement Information - Cash flow, etc. (Details) $ in Thousands				3 Months Ended		6 Months Ended
	May 31, 2018 USD ($) shares	Jan. 01, 2018	Dec. 31, 2017	May 31, 2018 USD ($) shares	May 31, 2017 USD ($)	May 31, 2018 USD ($) shares	May 31, 2017 USD ($)	Nov. 30, 2017 a shares
Supplemental Cash Flow Information
Number of acres sold | a								29
Increase (decrease) in value of available-for-sale securities: Investment in Centaur Media Plc							$ 295
Increase (decrease) in accounts payable and accrued liabilities related to additions to real estate assets						$ 4,584	443
Interest paid
Interest payments				$ 1,496	$ 1,320	2,929	2,552
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						133
Tax benefit						46
Income tax provision				$ 32	$ 2,553	$ 822	$ 2,102
2009 Stock Option Plan
Supplemental Cash Flow Information
Treasury shares | shares	18,405			18,405		18,405		3,535,000
Treasury stock	$ 721			$ 721		$ 721