Debt, Capital Leases and Royalty Obligation (Details Textual) (USD $)	3 Months Ended		12 Months Ended				3 Months Ended	12 Months Ended						0 Months Ended	3 Months Ended	12 Months Ended						12 Months Ended			12 Months Ended			12 Months Ended
	Dec. 31, 2012 oz	Sep. 30, 2010	Dec. 31, 2012 oz	Dec. 31, 2011	Dec. 31, 2010	Jan. 21, 2009	Dec. 31, 2012 3.25% Convertible Senior Notes due March 2028 [Member]	Dec. 31, 2012 3.25% Convertible Senior Notes due March 2028 [Member]	Dec. 31, 2011 3.25% Convertible Senior Notes due March 2028 [Member]	Dec. 31, 2010 3.25% Convertible Senior Notes due March 2028 [Member]	Dec. 31, 2012 Debt After Step Down [Member]	Dec. 31, 2012 Banco Bisa Line of Credit [Member]	Dec. 31, 2012 Banco de Credito Line of Credit [Member]	Aug. 16, 2012 Kensington Term Facility [Member]	Dec. 31, 2012 Kensington Term Facility [Member] oz	Dec. 31, 2012 Kensington Term Facility [Member]	Dec. 31, 2011 Kensington Term Facility [Member]	Dec. 31, 2011 Kensington Term Facility [Member]	Dec. 31, 2010 Kensington Term Facility [Member]	Dec. 31, 2012 Kensington Term Facility [Member] Call Option [Member] oz	Dec. 31, 2011 Kensington Term Facility [Member] Call Option [Member] oz	Dec. 31, 2012 Kensington Term Facility [Member] Put Option [Member] oz	Dec. 31, 2011 Kensington Term Facility [Member] Put Option [Member] oz	Mar. 31, 2012 Minimum [Member]	Dec. 31, 2012 LIBOR [Member]	Dec. 31, 2012 LIBOR [Member] Minimum [Member]	Dec. 31, 2012 LIBOR [Member] Maximum [Member]	Dec. 31, 2012 Alternate Base Rate [Member]	Dec. 31, 2012 Alternate Base Rate [Member] Minimum [Member]	Dec. 31, 2012 Alternate Base Rate [Member] Maximum [Member]
Debt Instrument [Line Items]
Ore on leach pad	$ 22,991,000		$ 22,991,000	$ 27,252,000
Debt and capital lease obligations (Textual) [Abstract]
Interest rate on notes							3.25%	3.25%	3.25%
Principal amount of bank loan							48,700,000	48,700,000
Current portion of debt and capital leases	55,983,000		55,983,000	32,602,000			48,081,000	48,081,000	0						0	0	15,398,000	15,398,000
Long-term Debt, Fair Value							48,200,000	48,200,000	49,200,000
Carrying value of the equity component							10,900,000	10,900,000	10,900,000
Interest expense							1,600,000
Interest Expense, Debt								1,581,000	1,581,000	2,394,000						2,339,000		4,383,000	2,017,000
Accretion of debt discount			2,536,000	2,324,000	2,543,000
Debt discount remaining	48,560,000		48,560,000				600,000	600,000
Effective interest rate on the notes							8.90%	8.90%
Borrowing under term facility	0		0									5.0	2.5
Line of credit facility, increase, additional borrowings			0
Line of credit facility, commitment fee amount	0.2
Description of variable rate basis																									LIBOR			alternate base rate
Basis spread on variable rate																										2.25%	3.25%		1.25%	2.25%
Ratio of consolidated debt to adjusted EBITDA	3.25		3.25								3
Ratio of adjusted EBITDA to interest expense	3		3
Percentage of tangible net worth																								90.00%
Percentage of net income	25.00%
Line of Credit Facility, Interest Rate at Period End												2.75%	2.50%
Repayments of Long-term Debt														68,600,000
Loss on debt extinguishments			1,036,000	5,526,000	20,300,000									1,000,000
Protection of gold under gold hedging program															243,750
Gold under collars protection																				97,000	136,000	122,000	190,000
Weighted average call feature of each collar															1,967.89		1,919.83	1,919.83
Weighted average put feature of each collar																	951.93	951.93				967.86
Outstanding amount of capital leases	11,400,000		11,400,000	27,000,000
Sale Portion Life of Mine						50.00%
Royalty Revenue in Cash						75,000,000
Value of Warrant Received as Royalty Consideration						3,000,000
Proceeds from Warrant Exercises		10,000,000
Royalty agreement minimum obligation for the period	400,000		400,000
Royalty Agreement Minimum Obligation for Per Month	4,167		4,167
Royalty Agreement Period	8 years		8 years	8 years		8 years
Percentage of Actual Gold Production			50.00%
Monthly Average Market Price of Gold Per Ounce			400
Percentage of Inflation Rate			1.00%
Payment of Royalty on Ounces of Gold	202,648,000		202,648,000
Percentage Royalty Obligation Payment Due to Affiliates			50.00%
Payments to Acquire Royalty Interests in Mining Properties			74,734,000	73,191,000	43,125,000
Additional Long term debt and capital lease obligations(Textual) [Abstract]
Implicit Interest Rate			30.00%
Accretion expense on royalty obligation discount			19,100,000	22,200,000
Accretion of Royalty Obligation			19,139,000	22,230,000	20,502,000
Remaining Minimum Obligation Under Royalty Agreements	61,900,000		61,900,000	72,100,000
Expensed Interest			26,169,000	34,774,000	30,942,000
Capitalized interest			$ (2,663,000)	$ (2,175,000)	$ (9,885,000)