Derivative Financial Instruments and Fair Value of Financial Instruments (Details)										3 Months Ended		9 Months Ended																																			3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2012 USD ($)	Sep. 30, 2012 2013 [Member]	Sep. 30, 2012 2013 [Member] MXN	Sep. 30, 2012 2014 [Member]	Sep. 30, 2012 2014 [Member] MXN	Sep. 30, 2012 Derivative Instruments Settle in Year 2014 Member [Member]	Sep. 30, 2012 Derivative Instruments Settle in Year 2014 Member [Member] MXN	Sep. 30, 2012 Thereafter [Member]	Sep. 30, 2012 Thereafter [Member] MXN	Sep. 30, 2012 Franco-Nevada warrant [Member] USD ($)	Sep. 30, 2011 Franco-Nevada warrant [Member] USD ($)	Sep. 30, 2012 Franco-Nevada warrant [Member] USD ($)	Sep. 30, 2011 Franco-Nevada warrant [Member] USD ($)	Sep. 30, 2012 Palmarejo gold production royalty [Member] 2013 [Member] USD ($) oz	Sep. 30, 2012 Palmarejo gold production royalty [Member] 2014 [Member] USD ($) oz	Sep. 30, 2012 Palmarejo gold production royalty [Member] Derivative Instruments Settle in Year 2014 Member [Member] USD ($) oz	Sep. 30, 2012 Palmarejo gold production royalty [Member] Thereafter [Member] USD ($) oz	Sep. 30, 2012 Mexican peso forward purchase contracts [Member] 2013 [Member] USD ($)	Sep. 30, 2012 Mexican peso forward purchase contracts [Member] 2014 [Member] USD ($)	Sep. 30, 2012 Mexican peso forward purchase contracts [Member] Derivative Instruments Settle in Year 2014 Member [Member] USD ($)	Sep. 30, 2012 Mexican peso forward purchase contracts [Member] Thereafter [Member] USD ($)	Sep. 30, 2012 Mexican Peso Notional Amount [Member] 2013 [Member] oz	Sep. 30, 2012 Mexican Peso Notional Amount [Member] 2014 [Member] oz	Sep. 30, 2012 Mexican Peso Notional Amount [Member] Derivative Instruments Settle in Year 2014 Member [Member] oz	Sep. 30, 2012 Mexican Peso Notional Amount [Member] Thereafter [Member] oz	Sep. 30, 2012 Silver ounces received from Mandalay [Member] 2013 [Member] USD ($) oz	Sep. 30, 2012 Silver ounces received from Mandalay [Member] 2014 [Member] USD ($) oz	Sep. 30, 2012 Silver ounces received from Mandalay [Member] Derivative Instruments Settle in Year 2014 Member [Member] USD ($) oz	Sep. 30, 2012 Silver ounces received from Mandalay [Member] Thereafter [Member] USD ($) oz	Sep. 30, 2012 Silver concentrate sales agreements [Member] 2013 [Member] USD ($) oz	Sep. 30, 2012 Silver concentrate sales agreements [Member] 2014 [Member] USD ($) oz	Sep. 30, 2012 Silver concentrate sales agreements [Member] Derivative Instruments Settle in Year 2014 Member [Member] USD ($) oz	Sep. 30, 2012 Silver concentrate sales agreements [Member] Thereafter [Member] USD ($) oz	Sep. 30, 2012 Gold concentrates sales agreements [Member] 2013 [Member] USD ($) oz	Sep. 30, 2012 Gold concentrates sales agreements [Member] 2014 [Member] USD ($) oz	Sep. 30, 2012 Gold concentrates sales agreements [Member] Derivative Instruments Settle in Year 2014 Member [Member] USD ($) oz	Sep. 30, 2012 Gold concentrates sales agreements [Member] Thereafter [Member] USD ($) oz	Sep. 30, 2012 Gold put options purchased [Member] 2013 [Member] USD ($) oz	Sep. 30, 2012 Gold put options purchased [Member] 2014 [Member] USD ($) oz	Sep. 30, 2012 Gold put options purchased [Member] Derivative Instruments Settle in Year 2014 Member [Member] USD ($) oz	Sep. 30, 2012 Gold put options purchased [Member] Thereafter [Member] USD ($) oz	Sep. 30, 2011 Gold call options sold [Member]	Sep. 30, 2012 Gold call options sold [Member] 2013 [Member] USD ($) oz	Sep. 30, 2012 Gold call options sold [Member] 2014 [Member] USD ($) oz	Sep. 30, 2012 Gold call options sold [Member] Derivative Instruments Settle in Year 2014 Member [Member] USD ($) oz	Sep. 30, 2012 Gold call options sold [Member] Thereafter [Member] USD ($) oz	Sep. 30, 2012 Foreign Exchange Forward [Member] Mexican peso forward purchase contracts [Member] USD ($)	Sep. 30, 2011 Foreign Exchange Forward [Member] Mexican peso forward purchase contracts [Member] USD ($)	Sep. 30, 2012 Foreign Exchange Forward [Member] Mexican peso forward purchase contracts [Member] USD ($)	Sep. 30, 2011 Foreign Exchange Forward [Member] Mexican peso forward purchase contracts [Member] USD ($)	Sep. 30, 2012 Line of Credit [Member] USD ($)	Sep. 30, 2012 Line of Credit [Member] USD ($)	Dec. 31, 2011 Line of Credit [Member] USD ($)
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net																																															$ 600,000	$ 4,100,000	$ 3,400,000	$ 3,800,000
Derivative Instruments, Loss Recognized in Income										10,900,000	11,900,000	35,000,000	29,100,000
Derivative instruments Settlement
Derivative, Notional Amount														8,392,000	25,097,000	24,895,000	45,831,000									769,000	0	0	0	14,343,000	0	0	0	6,508,000	0	0	0	720,000	1,800,000	720,000	0		0	0	720,000	0
Derivative average gold price in excess of minimum contractual Deduction Rate	400													504,000	502,000	498,000	492,000
Fair value of foreign exchange contracts																		8,700,000	8,700,000	0	0
Average rate (MXP/$)			12.85		13.52		0		0
Average forward price																										18.45	0	0	0
Derivative average price																										30.74	0	0	0					1,743	0	0	0
Average strike price		2,000	2,000	2,000	2,000	1,934	1,934	2,000	2,000																													923	928	979	1,010	2,000.00
Notional ounces														16,668	50,004	50,004	93,177					111,798	117,628,000	0	0	41,667	0	0	0	466,588	0	0	0	3,734	0	0	0	17,000	45,000	47,000	30,000		7,000	20,000	47,000	30,000
Derivative Instruments, Gain (Loss) Recognized in Income, Net																																															400,000	(100,000)	1,500,000	1,000,000
Weighted Average Put Feature of Each Collar																																																			$ 962.42	$ 923.34	$ 951.93