Share capital (Narrative) (Details) (USD $)	6 Months Ended		12 Months Ended	6 Months Ended		6 Months Ended	5 Months Ended	6 Months Ended	0 Months Ended		5 Months Ended	6 Months Ended
	May 31, 2014	May 31, 2013	Nov. 30, 2013	May 31, 2014 Number of RSU's [Member]	Apr. 30, 2012 Plan of Arrangement [Member]	May 31, 2014 Number of DSU's [Member]	Apr. 30, 2013 NovaGold Arrangement Options [Member]	May 31, 2014 NovaGold Arrangement Options [Member]	Dec. 05, 2012 Employees [Member] Number of RSU's [Member]	Dec. 05, 2012 Director [Member] Number of DSU's [Member]	May 31, 2014 Non-executive directors [Member]	May 31, 2014 Directors, Employees and Services Providers [Member] Approximations [Member] Stock-based Compensation [Member]	May 31, 2014 Employees and Directors [Member] Approximations [Member]
Common stock committed for issuance					6,181,352	20,685
Contributed surplus	$ 124,000		$ 152,000		$ 12,200,000
Common Stock, Shares Authorized
Stock options granted							2,189,040
Stock options granted, weighted average exercise price								$ 1.21
Share-based payments	251,000	4,993,000										20,000.00	200,000
Stock Issued on Vesting of Performance Share Units	14,166	14,180	16,586
Stock-based Compensation for NovaGold Arrangement Options								$ 10,000.00
Granted				0		22,564			1,295,500	750,000
Percentage of annual retainer in DSUs to be distributed											50.00%
Vesting of deferred share units	154,373					78,712