Share capital (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended	0 Months Ended	3 Months Ended		1 Months Ended	3 Months Ended		3 Months Ended	5 Months Ended	3 Months Ended	0 Months Ended	3 Months Ended	0 Months Ended	3 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Nov. 30, 2013	Dec. 05, 2013 Number of RSU's [Member]	Feb. 28, 2014 Number of RSU's [Member]	Apr. 30, 2012 Plan of Arrangement [Member]	Jan. 30, 2014 Number of DSU's [Member]	Feb. 28, 2014 Number of DSU's [Member]	Apr. 30, 2012 Number of DSU's [Member]	Feb. 28, 2014 NovaGold Arrangement Options [Member]	Apr. 30, 2013 NovaGold Arrangement Options [Member]	Feb. 28, 2013 Approximations [Member] Stock-based Compensation [Member]	Dec. 05, 2012 Employees [Member] Number of RSU's [Member]	Feb. 28, 2014 Employees [Member] Approximations [Member]	Dec. 05, 2012 Director [Member] Number of DSU's [Member]	Feb. 28, 2014 Non-executive directors [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										$ 1.18
Share-based payments	116,000	1,890,000										90,000		100,000
Stock Issued on Vesting of Performance Share Units	14,166	14,180	16,586
Stock-based Compensation for NovaGold Arrangement Options										$ 90,000
Granted					0			661					1,295,500		750,000
Units vested				425,833
Common shares issued for vested RSUs				425,833
Percentage of annual retainer in DSUs to be distributed																50.00%
Restricted stock outstanding				425,840
Vesting of deferred share units	75,661						75,661