Note 3 - Basis of Reporting and Significant Accounting Policies - Property and Equipment (Details)	6 Months Ended
	Jun. 30, 2018
Building and Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years
Building and Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	40 years
Mining Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	2 years
Mining Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	7 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	7 years
Vehicles [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years