Segment Reporting Segment Reporting (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Auramet [Member] | Palmarejo, San Bartolome, Kensington, Rochester [Member]
Revenue, Major Customer [Line Items]
Revenues	$ 111.7	$ 94.6	$ 50.8
Toronto-Dominion Bank [Member] | Palmarejo, Rochester [Member]
Revenue, Major Customer [Line Items]
Revenues	106.7	65.8	0
INTL Commodities [Member] | Palmarejo, San Bartolome, Rochester [Member]
Revenue, Major Customer [Line Items]
Revenues	84.6	58.0	112.6
China Gold [Member] | Kensington [Member]
Revenue, Major Customer [Line Items]
Revenues	81.5	43.8	108.9
Valcambi [Member] | Palmarejo, San Bartolome [Member]
Revenue, Major Customer [Line Items]
Revenues	77.2	414.4	385.5
Mitsui [Member] | Palmarejo, Rochester [Member]
Revenue, Major Customer [Line Items]
Revenues	$ 70.3	$ 65.6	$ 105.1