Note 14 - Guarantor Subsidiaries - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Parent Company [Member]
Cash flows from operating activities	$ 14,525	$ 11,043
Cash flows from investing activities:
Additions to properties, plants, and equipment	(348)	(436)
Acquisition of Mines Management, net of cash acquired	(3,931)	809
Other investing activities, net	(24,696)	61
Cash flows from financing activities:
Dividends paid to shareholders	(3,296)	3,210
Proceeds from (payments on) debt
Other financing activity, net	33,335	(29,949)
Effect of exchange rates on cash
Changes in cash and cash equivalents	15,589	(23,300)
Cash and cash equivalents at beginning of period	94,167	146,885
Cash and cash equivalents at end of period	109,756	123,585
Cash flows from operating activities	14,525	11,043
Additions to properties, plants, and equipment	(348)	(436)
Acquisition of Revett, net of cash acquired	3,931	(809)
Other investing activities, net	(24,696)	61
Dividends paid to shareholders	3,296	(3,210)
Proceeds from (payments on) debt
Guarantor Subsidiaries [Member]
Cash flows from operating activities	51,599	63,831
Cash flows from investing activities:
Additions to properties, plants, and equipment	(71,265)	(69,930)
Acquisition of Mines Management, net of cash acquired
Other investing activities, net	(816)	172
Cash flows from financing activities:
Dividends paid to shareholders
Proceeds from (payments on) debt	(7,477)
Other financing activity, net	24,522	24,294
Effect of exchange rates on cash
Changes in cash and cash equivalents	(3,437)	11,258
Cash and cash equivalents at beginning of period	42,692	33,824
Cash and cash equivalents at end of period	39,255	45,082
Cash flows from operating activities	51,599	63,831
Additions to properties, plants, and equipment	(71,265)	(69,930)
Acquisition of Revett, net of cash acquired
Other investing activities, net	(816)	172
Dividends paid to shareholders
Proceeds from (payments on) debt		(7,109)
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities	61,710	32,258
Cash flows from investing activities:
Additions to properties, plants, and equipment	(48,623)	(25,033)
Acquisition of Mines Management, net of cash acquired
Other investing activities, net	(3,647)	(903)
Cash flows from financing activities:
Dividends paid to shareholders
Proceeds from (payments on) debt	(658)
Other financing activity, net	(8,926)	(24,507)
Effect of exchange rates on cash	627	(4,044)
Changes in cash and cash equivalents	483	(23,169)
Cash and cash equivalents at beginning of period	18,350	28,956
Cash and cash equivalents at end of period	18,833	5,787
Cash flows from operating activities	61,710	32,258
Additions to properties, plants, and equipment	(48,623)	(25,033)
Acquisition of Revett, net of cash acquired
Other investing activities, net	(3,647)	(903)
Dividends paid to shareholders
Proceeds from (payments on) debt		(940)
Consolidated Entities [Member]
Cash flows from operating activities	173,114	78,968
Cash flows from investing activities:
Additions to properties, plants, and equipment	(120,236)	(95,399)
Acquisition of Mines Management, net of cash acquired	(3,931)	809
Other investing activities, net	(29,159)	(670)
Cash flows from financing activities:
Dividends paid to shareholders	(3,296)	3,210
Proceeds from (payments on) debt	(8,135)
Other financing activity, net	3,651	(1,998)
Effect of exchange rates on cash	627	(4,044)
Changes in cash and cash equivalents	12,635	(35,211)
Cash and cash equivalents at beginning of period	155,209	209,665
Cash and cash equivalents at end of period	167,844	174,454
Cash flows from operating activities	173,114	78,968
Additions to properties, plants, and equipment	(120,236)	(95,399)
Acquisition of Revett, net of cash acquired	3,931	(809)
Other investing activities, net	(29,159)	(670)
Dividends paid to shareholders	3,296	(3,210)
Proceeds from (payments on) debt		(8,049)
Consolidation, Eliminations [Member]
Cash flows from operating activities	45,280	(28,164)
Cash flows from investing activities:
Additions to properties, plants, and equipment
Acquisition of Mines Management, net of cash acquired
Other investing activities, net
Cash flows from financing activities:
Dividends paid to shareholders
Proceeds from (payments on) debt
Other financing activity, net	(45,280)	28,164
Effect of exchange rates on cash
Changes in cash and cash equivalents
Cash and cash equivalents at beginning of period
Cash and cash equivalents at end of period
Cash flows from operating activities	45,280	(28,164)
Additions to properties, plants, and equipment
Acquisition of Revett, net of cash acquired
Other investing activities, net
Dividends paid to shareholders
Proceeds from (payments on) debt
Cash flows from operating activities	173,114	78,968
Additions to properties, plants, and equipment	(120,236)	(95,399)
Acquisition of Mines Management, net of cash acquired	(3,931)	(809)
Proceeds from (payments on) debt	(1,807)	(216)
Effect of exchange rates on cash	627	(4,044)
Changes in cash and cash equivalents	12,635	(35,211)
Cash and cash equivalents at beginning of period	155,209	209,665
Cash and cash equivalents at end of period	167,844	174,454
Cash flows from operating activities	173,114	78,968
Additions to properties, plants, and equipment	(120,236)	(95,399)
Acquisition of Revett, net of cash acquired	$ 3,931	$ 809