Note 14 - Guarantor Subsidiaries (Details) - Condensed Consolidating Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Assets
Cash and cash equivalents	$ 237,836	$ 190,984	$ 232,194	$ 266,463
Other current assets	152,050	91,914
Properties, plants, and equipment - net	1,776,554	996,659
Other non-current assets	102,572	98,733
Total assets	2,269,012	1,378,290
Liabilities and Shareholders' Equity
Current liabilities	177,904	94,987
Long-term debt	490,417	11,935
Non-current portion of accrued reclamation	49,862	93,370
Non-current deferred tax liability	171,260
Other non-current liabilities	39,180	40,047
Shareholders' equity	1,327,786	1,137,951
Total liabilities and shareholders' equity	2,269,012	1,378,290
Consolidation, Eliminations [Member]
Assets
Other current assets	2,244	18,091
Intercompany receivable (payable)	151,295	26,109
Investments in subsidiaries	(1,196,577)	(918,526)
Other non-current assets	(85,053)	(76,839)
Total assets	(1,128,091)	(951,165)
Liabilities and Shareholders' Equity
Current liabilities	(12,994)	(30,976)
Non-current deferred tax liability	80,120
Other non-current liabilities		(1,663)
Shareholders' equity	(1,195,217)	(918,526)
Total liabilities and shareholders' equity	(1,128,091)	(951,165)
Parent Company [Member]
Assets
Cash and cash equivalents	116,255	132,266	123,070	97,850
Other current assets	11,317	7,399
Properties, plants, and equipment - net	498
Intercompany receivable (payable)	540,038	113,234
Investments in subsidiaries	1,196,577	918,526
Other non-current assets	11,894	3,059
Total assets	1,876,579	1,174,484
Liabilities and Shareholders' Equity
Current liabilities	27,973	3,726
Long-term debt	490,417
Other non-current liabilities	30,403	32,807
Shareholders' equity	1,327,786	1,137,951
Total liabilities and shareholders' equity	1,876,579	1,174,484
Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	29,864	57,075	108,406	168,433
Other current assets	103,839	65,658
Properties, plants, and equipment - net	1,041,328	991,476
Intercompany receivable (payable)	(120,727)	(64,893)
Other non-current assets	163,073	164,913
Total assets	1,217,377	1,214,229
Liabilities and Shareholders' Equity
Current liabilities	144,897	121,221
Long-term debt	12,559	11,875
Non-current portion of accrued reclamation	38,061	92,825
Non-current deferred tax liability	14,124
Other non-current liabilities	8,033	8,651
Shareholders' equity	999,703	979,657
Total liabilities and shareholders' equity	1,217,377	1,214,229
Non-Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	91,717	1,643	718	180
Other current assets	34,650	766
Properties, plants, and equipment - net	734,728	5,183
Intercompany receivable (payable)	(570,606)	(74,450)
Other non-current assets	12,658	7,600
Total assets	303,147	(59,258)
Liabilities and Shareholders' Equity
Current liabilities	18,028	1,016
Long-term debt	44	60
Non-current portion of accrued reclamation	11,801	545
Non-current deferred tax liability	77,016
Other non-current liabilities	744	252
Shareholders' equity	195,514	(61,131)
Total liabilities and shareholders' equity	$ 303,147	$ (59,258)