Note 6 - Business Segments and Sales of Products - Identifiable Assets by Reporting Segments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Identifiable assets:
Identifiable assets	$ 2,392,594	$ 2,364,957
Greens Creek [Member]
Identifiable assets:
Identifiable assets	678,862	671,960
Lucky Friday [Member]
Identifiable assets:
Identifiable assets	429,213	432,400
Casa Berardi [Member]
Identifiable assets:
Identifiable assets	792,891	804,505
San Sebastian [Member]
Identifiable assets:
Identifiable assets	68,812	62,198
Other Segments [Member]
Identifiable assets:
Identifiable assets	$ 424,016	$ 393,894