Note 7 - Business Segments and Sales of Products - Identifiable Assets by Reporting Segments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Identifiable assets	$ 2,710,258	$ 2,345,158
Greens Creek [Member]
Identifiable assets	651,814	671,960
Lucky Friday [Member]
Identifiable assets	429,334	432,400
Casa Berardi [Member]
Identifiable assets	758,415	784,706
San Sebastian [Member]
Identifiable assets	47,352	62,198
Nevada Operations [Member]
Identifiable assets	539,410
Other Segments [Member]
Identifiable assets	$ 283,933	$ 393,894