Derivative Financial Instruments and Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011 oz	Sep. 30, 2011
Derivative instruments Settlement
Average forward price	1.380
Palmarejo gold royalty [Member] | 2012 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	27,707
Derivative average gold price in excess of minimum contractual Deduction Rate	496
Notional ounces	55,833
Palmarejo gold royalty [Member] | 2013 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	25,097
Derivative average gold price in excess of minimum contractual Deduction Rate	502
Notional ounces	50,004
Palmarejo gold royalty [Member] | 2014 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	24,895
Derivative average gold price in excess of minimum contractual Deduction Rate	498
Notional ounces	50,004
Palmarejo gold royalty [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, Notional Amount	49,563
Derivative average gold price in excess of minimum contractual Deduction Rate	492
Notional ounces	100,805
Mexican peso forward purchase contracts [Member] | 2012 [Member]
Derivative instruments Settlement
Fair value of foreign exchange contracts	25,500
Average forward price	12.4
Mexican peso forward purchase contracts [Member] | 2013 [Member]
Derivative instruments Settlement
Fair value of foreign exchange contracts	0
Average forward price	0
Mexican peso forward purchase contracts [Member] | 2014 [Member]
Derivative instruments Settlement
Fair value of foreign exchange contracts	0
Average forward price	0
Mexican peso forward purchase contracts [Member] | Thereafter [Member]
Derivative instruments Settlement
Fair value of foreign exchange contracts	0
Average forward price	0
Mexican Peso Notional Amount [Member] | 2012 [Member]
Derivative instruments Settlement
Notional ounces	316,090
Mexican Peso Notional Amount [Member] | 2013 [Member]
Derivative instruments Settlement
Notional ounces	0
Mexican Peso Notional Amount [Member] | 2014 [Member]
Derivative instruments Settlement
Notional ounces	0
Mexican Peso Notional Amount [Member] | Thereafter [Member]
Derivative instruments Settlement
Notional ounces	0
Silver ounces received from Mandalay [Member] | 2012 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	1,535
Average forward price	18.42
Notional ounces	83,333
Silver ounces received from Mandalay [Member] | 2013 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Average forward price	0
Notional ounces	0
Silver ounces received from Mandalay [Member] | 2014 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Average forward price	0
Notional ounces	0
Silver ounces received from Mandalay [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Average forward price	0
Notional ounces	0
Silver concentrate sales agreements [Member] | 2012 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	6,219
Derivative average price	32.74
Notional ounces	189,975
Silver concentrate sales agreements [Member] | 2013 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Derivative average price	0
Notional ounces	0
Silver concentrate sales agreements [Member] | 2014 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Derivative average price	0
Notional ounces	0
Silver concentrate sales agreements [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Derivative average price	0
Notional ounces	0
Gold concentrates sales agreements [Member] | 2012 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	16,309
Derivative average price	1,681.00
Notional ounces	9,701
Gold concentrates sales agreements [Member] | 2013 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Derivative average price	0
Notional ounces	0
Gold concentrates sales agreements [Member] | 2014 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Derivative average price	0
Notional ounces	0
Gold concentrates sales agreements [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Derivative average price	0
Notional ounces	0
Gold put options purchased [Member] | 2012 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	2,880
Average strike price	923.00
Notional ounces	68,000
Gold put options purchased [Member] | 2013 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	1,800
Average strike price	928.00
Notional ounces	45,000
Gold put options purchased [Member] | 2014 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	720
Average strike price	979.00
Notional ounces	47,000
Gold put options purchased [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Average strike price	1,010.00
Notional ounces	30,000
Gold call options sold [Member]
Derivative instruments Settlement
Notional ounces	35,000	72,750,000
Gold call options sold [Member] | 2012 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Average strike price	2,000.00
Notional ounces	14,000
Gold call options sold [Member] | 2013 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	1,800
Average strike price	1,827.00
Notional ounces	45,000
Gold call options sold [Member] | 2014 [Member]
Derivative instruments Settlement
Derivative, Notional Amount	720
Average strike price	1,934.00
Notional ounces	47,000
Gold call options sold [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, Notional Amount	0
Average strike price	2,000.00
Notional ounces	30,000