Note 17 - Guarantor Subsidiaries (Details) - Condensed Consolidating Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 212,175	$ 190,984	$ 266,463	$ 283,606
Other current assets	8,324	8,858
Properties, plants, and equipment - net	1,791,601	996,659
Other non-current assets	5,867	1,883
Total assets	2,232,119	1,378,290	1,396,090
Liabilities and Stockholders' Equity
Current liabilities	151,479	94,987
Long-term debt	490,726
Non-current deferred tax liability	164,861
Other non-current liabilities	37,536	40,047
Stockholders' equity	1,326,419	1,137,951	1,140,113	962,253
Total liabilities and stockholders' equity	2,232,119	1,378,290
Parent [Member]
Assets
Cash and cash equivalents	126,271	132,266	97,850	190,000
Other current assets	4,795	7,399
Properties, plants, and equipment - net	803
Intercompany receivable (payable)	547,074	113,234
Investments in subsidiaries	1,176,293	918,526
Other non-current assets	5,248	3,059
Total assets	1,860,484	1,174,484
Liabilities and Stockholders' Equity
Current liabilities	10,058	3,726
Long-term debt	490,726
Other non-current liabilities	33,281	32,807
Stockholders' equity	1,326,419	1,137,951
Total liabilities and stockholders' equity	1,860,484	1,174,484
Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	40,009	57,075	168,433	93,125
Other current assets	75,083	65,658
Properties, plants, and equipment - net	1,052,102	991,476
Intercompany receivable (payable)	(131,599)	(64,893)
Other non-current assets	164,563	164,913
Total assets	1,200,158	1,214,229
Liabilities and Stockholders' Equity
Current liabilities	117,422	121,221
Long-term debt	14,292	11,875
Non-current portion of accrued reclamation	38,426	92,825
Non-current deferred tax liability	16,430
Other non-current liabilities	4,043	8,651
Stockholders' equity	1,009,545	979,657
Total liabilities and stockholders' equity	1,200,158	1,214,229
Non-Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	45,895	1,643	180	481
Other current assets	33,129	766
Properties, plants, and equipment - net	738,696	5,183
Intercompany receivable (payable)	(464,634)	(74,450)
Other non-current assets	11,115	7,600
Total assets	364,201	(59,258)
Liabilities and Stockholders' Equity
Current liabilities	24,000	1,016
Long-term debt	40	60
Non-current portion of accrued reclamation	8,340	545
Non-current deferred tax liability	164,861
Other non-current liabilities	212	252
Stockholders' equity	166,748	(61,131)
Total liabilities and stockholders' equity	364,201	(59,258)
Consolidation, Eliminations [Member]
Assets
Other current assets	18,453	18,091
Intercompany receivable (payable)	49,159	26,109
Investments in subsidiaries	(1,176,293)	(918,526)
Other non-current assets	(84,043)	(76,839)
Total assets	(1,192,724)	(951,165)
Liabilities and Stockholders' Equity
Current liabilities		(30,976)
Non-current deferred tax liability	(16,431)
Other non-current liabilities		(1,663)
Stockholders' equity	(1,176,293)	(918,526)
Total liabilities and stockholders' equity	(1,192,724)	(951,165)
Consolidated [Member]
Assets
Cash and cash equivalents	212,175	190,984	266,463	283,606
Other current assets	131,460	91,914
Properties, plants, and equipment - net	1,791,601	996,659
Other non-current assets	96,883	98,733
Total assets	2,232,119	1,378,290
Liabilities and Stockholders' Equity
Current liabilities	151,480	94,987
Long-term debt	505,058	11,935
Non-current portion of accrued reclamation	46,766	93,370
Non-current deferred tax liability	164,860
Other non-current liabilities	37,536	40,047
Stockholders' equity	1,326,419	1,137,951
Total liabilities and stockholders' equity	$ 2,232,119	$ 1,378,290