Derivative Financial Instruments (Details 2) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Revenue		$ 162,552	$ 170,938	$ 481,770	$ 495,133
Costs applicable to sales	[1]	(120,237)	(125,910)	(354,397)	(351,492)
Fair value adjustments, net		5,786	16,105	3,657	(3,611)
Fair value adjustments, net		4,116	11,076	4,858	(6,182)
Concentrate Sales Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives		82	(684)	373	188
Forward foreign exchange contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Costs applicable to sales		0	0	0	(924)
Fair value adjustments, net		0	(57)	0	901
Mexican peso forward purchase contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fair value adjustments, net		0	(57)	0	901
Silver and gold options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives			3,100
Fair value adjustments, net		1,051	$ 3,081	1,238	213
Derivative, Gain (Loss) on Derivative, Net		$ 1,051		$ 2,662	$ 1,300

[1] Excludes amortization.