Note 14 - Guarantor Subsidiaries (Details) - Condensed Consolidating Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	$ 78,968	$ 58,768
Cash flows from investing activities:
Additions to properties, plants, and equipment	(95,399)	(90,697)
Acquisition of Revett, net of cash acquired	(809)
Cash flows from financing activities:
Effect of exchange rates on cash	(4,044)	(2,124)
Changes in cash and cash equivalents	(35,211)	10,185
Cash and cash equivalents at beginning of period	209,665	212,175
Cash and cash equivalents at end of period	174,454	222,360
Consolidation, Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	(28,164)	(31,968)
Cash flows from financing activities:
Other financing activity	28,164	31,968
Consolidated [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	78,968	58,768
Cash flows from investing activities:
Additions to properties, plants, and equipment	(95,399)	(90,697)
Acquisition of Revett, net of cash acquired	(809)
Other investing activities	(670)	4,201
Cash flows from financing activities:
Dividends paid to stockholders	(3,210)	(3,043)
Payments on debt	(8,049)	(6,893)
Other financing activity	(1,998)	49,973
Effect of exchange rates on cash	(4,044)	(2,124)
Changes in cash and cash equivalents	(35,211)	10,185
Cash and cash equivalents at beginning of period	209,665	212,175
Cash and cash equivalents at end of period	174,454	222,360
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	11,043	37,533
Cash flows from investing activities:
Additions to properties, plants, and equipment	(436)	(1,057)
Acquisition of Revett, net of cash acquired	(809)
Other investing activities	61
Cash flows from financing activities:
Dividends paid to stockholders	(3,210)	(3,043)
Other financing activity	(29,949)	(7,965)
Changes in cash and cash equivalents	(23,300)	25,468
Cash and cash equivalents at beginning of period	146,885	126,271
Cash and cash equivalents at end of period	123,585	151,739
Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	63,831	32,896
Cash flows from investing activities:
Additions to properties, plants, and equipment	(69,930)	(58,472)
Other investing activities	172	358
Cash flows from financing activities:
Payments on debt	(7,109)	(6,878)
Other financing activity	24,294	40,292
Changes in cash and cash equivalents	11,258	8,196
Cash and cash equivalents at beginning of period	33,824	40,009
Cash and cash equivalents at end of period	45,082	48,205
Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	32,258	20,307
Cash flows from investing activities:
Additions to properties, plants, and equipment	(25,033)	(31,168)
Other investing activities	(903)	3,843
Cash flows from financing activities:
Payments on debt	(940)	(15)
Other financing activity	(24,507)	(14,322)
Effect of exchange rates on cash	(4,044)	(2,124)
Changes in cash and cash equivalents	(23,169)	(23,479)
Cash and cash equivalents at beginning of period	28,956	45,895
Cash and cash equivalents at end of period	$ 5,787	$ 22,416