Share capital - Narrative (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Feb. 28, 2021 USD ($) $ / shares shares	Feb. 28, 2021 USD ($) $ / shares $ / shares shares	Feb. 29, 2020 USD ($) $ / shares shares	Feb. 29, 2020 USD ($) $ / shares	Nov. 30, 2020 shares	Nov. 30, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, conversion | shares	1
Stock-based compensation | $	$ (2,148)		$ (1,196)
Non-vested stock options outstanding | shares	11,520,277	11,520,277
Weighted average exercise price options outstanding | $ / shares	$ 1.90	$ 1.90
Aggregate intrinsic value, vested options | $	$ 3,300	$ 3,300	5,900	$ 5,900
Aggregate intrinsic value, options exercised | $	$ 170		40
Share capital
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock committed for issuance | shares	144,214,485	144,214,485			144,137,850	140,427,761
Nonvested Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested stock options outstanding | shares	3,374,150	3,374,150
Weighted average exercise price options outstanding | $ / shares	$ 2.07	$ 2.07
Stock option expense not yet recognized | $	$ 1,630	$ 1,630
Period for recognition of stock compensation expense	2 years
NovaGold DSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted units | shares	19,992
Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation | $	$ 40		$ 40
Employees, Consultants And Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted, expiration period	5 years
Stock options granted | shares	3,374,150		2,050,000
Vesting period			2 years
Weighted-average exercise price | $ / shares		$ 2.52		$ 3.02
Stock options granted, weighted average fair value | $ / shares	$ 0.84		$ 0.99
Directors Employees And Services Providers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation | $	$ 2,100		$ 1,160