Mineral Properties - Additional Information (Details)	Sep. 30, 2018 a MiningClaim
Sleeper Gold Project | Nevada
Mineral Properties [Line Items]
Unpatented mining claims	2,322
Area covered by lode mining claims | a	38,300
Grassy Mountain Project | Oregon
Mineral Properties [Line Items]
Unpatented lode mining claims	418
Patented lode mining claims	3
Mill site mining claims	9
Association placer claims	6
Area covered by mining claims | a	9,300