Note 14 - Guarantor Subsidiaries (Details) - Condensed Consolidating Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	$ 52,173	$ 57,029
Cash flows from financing activities:
Effect of exchange rates on cash	(2,259)	250
Changes in cash and cash equivalents	(18,091)	9,908
Cash and cash equivalents at beginning of period	209,665	212,175
Cash and cash equivalents at end of period	191,574	222,083
Additions to properties, plants, and equipment	(58,272)	(57,461)
Acquisition of Revett, net of cash acquired	(809)
Consolidation, Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	(35,939)	1,574
Cash flows from financing activities:
Other financing activity	35,939	(1,574)
Consolidated [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	52,173	57,029
Cash flows from financing activities:
Dividends paid to stockholders	(2,126)	(1,991)
Payments on debt	(4,940)	(4,525)
Other financing activity	(1,064)	12,034
Effect of exchange rates on cash	(2,259)	250
Changes in cash and cash equivalents	(18,091)	9,908
Cash and cash equivalents at beginning of period	209,665	212,175
Cash and cash equivalents at end of period	191,574	222,083
Additions to properties, plants, and equipment	(58,272)	(57,461)
Acquisition of Revett, net of cash acquired	(809)
Other investing activities	(794)	4,572
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	31,482	14,846
Cash flows from financing activities:
Dividends paid to stockholders	(2,126)	(1,991)
Other financing activity	(47,645)	21,984
Changes in cash and cash equivalents	(19,473)	34,103
Cash and cash equivalents at beginning of period	146,885	126,271
Cash and cash equivalents at end of period	127,412	160,374
Additions to properties, plants, and equipment	(436)	(736)
Acquisition of Revett, net of cash acquired	(809)
Other investing activities	61
Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	49,275	46,829
Cash flows from financing activities:
Payments on debt	(4,349)	(4,525)
Other financing activity	17,852	(11,021)
Changes in cash and cash equivalents	22,082	(1,370)
Cash and cash equivalents at beginning of period	33,824	40,009
Cash and cash equivalents at end of period	55,906	38,639
Additions to properties, plants, and equipment	(40,963)	(32,891)
Other investing activities	267	238
Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Cash flows from operating activities	7,355	(6,220)
Cash flows from financing activities:
Payments on debt	(591)
Other financing activity	(7,210)	2,645
Effect of exchange rates on cash	(2,259)	250
Changes in cash and cash equivalents	(20,700)	(22,825)
Cash and cash equivalents at beginning of period	28,956	45,895
Cash and cash equivalents at end of period	8,256	23,070
Additions to properties, plants, and equipment	(16,873)	(23,834)
Other investing activities	$ (1,122)	$ 4,334