Significant Customers (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Valcambi [Member] | Palmarejo San Bartolome [Member]
Customers total revenue
Customers total revenue	$ 414.4	$ 385,500	$ 174,100
Auramet [Member] | Palmarejo [Member]
Customers total revenue
Customers total revenue	94.6	50,800	79,000
Penoles [Member] | Martha [Member]
Customers total revenue
Customers total revenue	0.3	13,300	53,900
China Gold [Member] | Kensington [Member]
Customers total revenue
Customers total revenue	43.8	108,900	23,600
International Commodities [Member] | Palmarejo San Bartolome Rochester [Member]
Customers total revenue
Customers total revenue	58.0	112,600	36,700
Mitsui [Member] | Palmarejo San Bartolome Rochester [Member]
Customers total revenue
Customers total revenue	$ 65.6	$ 105,100	$ 45,900