Share capital (Narrative) (Details)		1 Months Ended	2 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended	137 Months Ended
	Jun. 19, 2015	Sep. 17, 2015 USD ($) shares	Aug. 31, 2014 shares	Aug. 31, 2015 USD ($) $ / shares shares	Aug. 31, 2015 USD ($) $ / shares CAD / shares shares	Aug. 31, 2014 USD ($)	Aug. 31, 2015 USD ($) $ / shares shares	Aug. 31, 2014 USD ($)	Nov. 30, 2014 USD ($) $ / shares shares	Aug. 31, 2015 USD ($) $ / shares shares	May. 31, 2014 USD ($)	Apr. 30, 2012 USD ($) shares
Contributed surplus				$ 124,000	$ 124,000		$ 124,000		$ 124,000	$ 124,000
Common Stock, Shares Authorized | shares
Stock options granted | shares							1,728,350
Stock options exercised | shares							(33,333)		46,929
Proceeds from stock options exercised				$ 0		$ 0	$ 0	$ 16,000		$ 36,000
Stock options granted, weighted average exercise price | $ / shares							$ 0.47
Stock-based compensation							$ 582,000	321,000
Non-vested stock options outstanding | shares				3,236,683	3,236,683		3,236,683		1,741,666	3,236,683
Weighted average exercise price options outstanding | $ / shares				$ 0.71	$ 0.71		$ 0.71		$ 1.11	$ 0.71
Stock option expense				$ 0		0	$ 0	0		$ 316,000
Aggregate intrinsic value, vested options				70,000	$ 70,000		70,000			70,000	$ 0
Aggregate intrinsic value, options exercised							$ 0
Vesting of deferred share units | shares							119,139		154,373
Proceeds from private placement, net				$ 0		$ 7,231,000	$ 0	7,231,000		$ 7,231,000
Non-Vested Options [Member]
Non-vested stock options outstanding | shares				1,308,910	1,308,910		1,308,910			1,308,910
Weighted average exercise price options outstanding | $ / shares				$ 0.69	$ 0.69		$ 0.69			$ 0.69
Number of RSU's [Member]
Granted | shares							458,032
Plan of Arrangement [Member]
Common stock committed for issuance | shares												6,181,352
Contributed surplus												$ 12,200,000
Number of DSU's [Member]
Common stock committed for issuance | shares				20,685	20,685		20,685			20,685
Granted | shares							263,952
Stock-based Compensation [Member]
Stock-based compensation							$ 120,000	300,000
NovaGold Arrangement Options [Member]
Stock based compensation, recovery							$ 0
Non-vested stock options outstanding | shares				530,105	530,105		530,105		721,415	530,105
Weighted average exercise price options outstanding | $ / shares				$ 4.89	$ 4.89		$ 4.89		$ 5.06	$ 4.89
Stock-based Compensation for NovaGold Arrangement Options								10,000
Aggregate intrinsic value, vested options				$ 40,000	$ 40,000		$ 40,000			$ 40,000	$ 110,000
Options expired | shares							(186,954)
Sunward Arrangement Options [Member]
Stock options exercised | shares		347,999
Proceeds from stock options exercised		$ 188,000
Stock-based compensation				$ 30,000
Non-vested stock options outstanding | shares				2,505,000	2,505,000		2,505,000		0	2,505,000
Weighted average exercise price options outstanding | $ / shares				$ 0.82	$ 0.82		$ 0.82		$ 0	$ 0.82
Aggregate intrinsic value, vested options				$ 190,000	$ 190,000		$ 190,000			$ 190,000
Exchange ratio	0.3
Options expired | shares							2,022,001
Stock options amended from expiry | shares							135,000
Approximations [Member] | Non-Vested Options [Member]
Stock option expense				$ 100,000
Minimum [Member]
Vesting terms				0 years
New Employees [Member]
Stock options granted | shares			0				1,728,350
Stock options granted, weighted average exercise price | (per share)					$ 0.61		$ 0.21
Directors, Employees and Services Providers [Member]
Stock-based compensation							$ 430,000	$ 10,000