Note 6 - Mineral Property (Details Textual) - Copper Canyon Property [Member]	12 Months Ended
Nov. 30, 2017
Mineral Properties, Ownership Percentage	40.00%
Galore Creek [Member]
Mineral Properties, Ownership Percentage	60.00%

Percentage of the mineral properties owned by the reporting entity or other entity.

No definition available.

Name:	ng_MineralPropertiesOwnershipPercentage
Namespace Prefix:	ng_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration