Equity method investment - Financial information (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Aug. 31, 2021	Aug. 31, 2020	May 31, 2020	Aug. 31, 2021	Aug. 31, 2020	Nov. 30, 2020	Feb. 11, 2020
The carrying value of Trilogy's 50% investment in Ambler Metals LLC
Share of loss on equity investment for the six-month period ending May 31, 2021	$ (6,072)	$ (1,094)		$ (8,892)	$ (1,833)
Investment in Ambler Metals LLC.	164,253			164,253		$ 173,145
Ambler Metals LLC's Balance Sheet and Comprehensive loss
Total Assets	172,255			172,255		185,265
Amortization				16	75
General and administrative expense	425	$ 265		1,188	1,349
Ambler Metals LLC
The carrying value of Trilogy's 50% investment in Ambler Metals LLC
Investment in Ambler Metals LLC.						173,145	$ 176,000
Share of loss on equity investment for the six-month period ending May 31, 2021				(8,892)
Investment in Ambler Metals LLC.	164,253			164,253			$ 176,000
Ambler Metals LLC's Balance Sheet and Comprehensive loss
Current assets: Cash, deposits and prepaid expenses	69,452			69,452		82,226
Non - current assets: Property, equipment and mineral properties	32,231			32,231		31,287
Loan receivable from South32	56,070			56,070		58,478
Current liabilities: Accounts payable and accrued liabilities	(4,083)			(4,083)		(1,445)
Non - current liabilities: Lease obligation	(957)			(957)		(51)
Total Assets	152,713			152,713		$ 170,495
Amortization	22		$ 37	55	87
Mineral properties expense	11,139		1,329	15,109	2,409
General and administrative expense	1,243		1,168	3,426	2,072
Interest income	(260)		(345)	(807)	(902)
Comprehensive loss	$ 12,144		$ 2,189	$ 17,783	$ 3,666