Mineral properties and development costs - Mineral property expenses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	May 31, 2019	May 31, 2020	May 31, 2019
Mineral property expense	$ 2,906	$ 1,545	$ 4,441
Alaska, USA [Member]
Community	146	137	264
Drilling	173		173
Engineering	303	723	624
Environmental	136	99	271
Geochemistry and geophysics	593	12	758
Land and permitting	174	134	360
Project support	778	249	1,004
Other income			(1)
Wages and benefits	603	191	988
Mineral property expense	$ 2,906	$ 1,545	$ 4,441