Note 14 - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Parent Company [Member]
Cash flows from operating activities	$ 22,190	$ 31,482
Investing activities:
Additions to properties, plants, and equipment	(40)	(436)
Other investing activities, net	(15,248)	61
Financing activities:
Dividends paid to stockholders	(2,190)	(2,126)
Payments on debt	(1,339)
Other financing activity	(4,948)	(47,645)
Effect of exchange rate changes on cash
Changes in cash and cash equivalents	8,321	(19,473)
Cash and cash equivalents at beginning of period	94,167	146,885
Cash and cash equivalents at end of period	102,488	127,412
Cash flows from operating activities	22,190	31,482
Additions to properties, plants, and equipment	(40)	(436)
Acquisition of Revett, net of cash acquired		(809)
Other investing activities, net	(15,248)	61
Guarantor Subsidiaries [Member]
Cash flows from operating activities	(8,639)	49,275
Investing activities:
Additions to properties, plants, and equipment	(43,677)	(40,963)
Other investing activities, net	317	267
Financing activities:
Dividends paid to stockholders
Payments on debt	(3,836)	(4,349)
Other financing activity	36,863	17,852
Effect of exchange rate changes on cash
Changes in cash and cash equivalents	(18,972)	22,082
Cash and cash equivalents at beginning of period	42,692	33,824
Cash and cash equivalents at end of period	23,720	55,906
Cash flows from operating activities	(8,639)	49,275
Additions to properties, plants, and equipment	(43,677)	(40,963)
Acquisition of Revett, net of cash acquired
Other investing activities, net	317	267
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities	40,815	7,355
Investing activities:
Additions to properties, plants, and equipment	(33,243)	(16,873)
Other investing activities, net	(3,900)	(1,122)
Financing activities:
Dividends paid to stockholders
Payments on debt	(520)	(591)
Other financing activity	(5,385)	(7,210)
Effect of exchange rate changes on cash	1,288	(2,259)
Changes in cash and cash equivalents	(945)	(20,700)
Cash and cash equivalents at beginning of period	18,350	28,956
Cash and cash equivalents at end of period	17,405	8,256
Cash flows from operating activities	40,815	7,355
Additions to properties, plants, and equipment	(33,243)	(16,873)
Acquisition of Revett, net of cash acquired
Other investing activities, net	(3,900)	(1,122)
Consolidation, Eliminations [Member]
Cash flows from operating activities	31,772	(35,939)
Investing activities:
Additions to properties, plants, and equipment
Other investing activities, net
Financing activities:
Dividends paid to stockholders
Payments on debt
Other financing activity	(31,772)	35,939
Effect of exchange rate changes 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	31,772	(35,939)
Additions to properties, plants, and equipment
Acquisition of Revett, net of cash acquired
Other investing activities, net
Consolidated [Member]
Cash flows from operating activities	86,138	52,173
Investing activities:
Additions to properties, plants, and equipment	(76,960)	(58,272)
Other investing activities, net	(18,831)	(794)
Financing activities:
Dividends paid to stockholders	(2,190)	(2,126)
Payments on debt	(5,695)	(4,940)
Other financing activity	4,654	(1,064)
Effect of exchange rate changes on cash	1,288	(2,259)
Changes in cash and cash equivalents	(11,596)	(18,091)
Cash and cash equivalents at beginning of period	155,209	209,665
Cash and cash equivalents at end of period	143,613	191,574
Cash flows from operating activities	86,138	52,173
Additions to properties, plants, and equipment	(76,960)	(58,272)
Acquisition of Revett, net of cash acquired		(809)
Other investing activities, net	(18,831)	(794)
Cash flows from operating activities	86,138	52,173
Additions to properties, plants, and equipment	(76,960)	(58,272)
Effect of exchange rate changes on cash	1,288	(2,259)
Changes in cash and cash equivalents	(11,596)	(18,091)
Cash and cash equivalents at beginning of period	155,209	209,665
Cash and cash equivalents at end of period	143,613	191,574
Cash flows from operating activities	86,138	52,173
Additions to properties, plants, and equipment	(76,960)	(58,272)
Acquisition of Revett, net of cash acquired		$ 809