Derivative Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Fair value adjustments, net	$ 3,618	$ 82,768	$ (23,487)
Mark-to-market gains or losses on derivatives	(158)	80,928	(23,426)
Concentrate Sales Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(123)	(1,995)	1,682
Forward foreign exchange contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Costs applicable to sales	924	589	1,621
Fair value adjustments, net	(16)	(985)	3,264
Palmarejo gold production royalty [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value adjustments, net	(2,001)	76,200	(31,053)
Silver and gold options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value adjustments, net	$ 1,058	$ 7,119	$ 4,302