Mining Properties (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Mining Properties
Operational mining properties:	$ 658,774		$ 649,905
Accumulated depletion	(215,575)		(203,416)
Operational mining properties, net	443,199		446,489
Mineral interest	1,729,064	[1]	1,729,064	[1]
Accumulated depletion	(197,041)		(174,668)
Mineral interest, net	1,532,023		1,554,396
Non-producing and developmental properties(B)	142		142
Total mining properties	1,975,364		2,001,027
Palmarejo [Member]
Mining Properties
Operational mining properties:	138,333		134,296
Accumulated depletion	(61,065)		(53,060)
Operational mining properties, net	77,268		81,236
Mineral interest	1,658,389	[1]	1,658,389	[1]
Accumulated depletion	(179,015)		(158,627)
Mineral interest, net	1,479,374		1,499,762
Non-producing and developmental properties(B)	0		0
Total mining properties	1,556,642		1,580,998
San Bartolome [Member]
Mining Properties
Operational mining properties:	69,019		68,684
Accumulated depletion	(15,871)		(14,989)
Operational mining properties, net	53,148		53,695
Mineral interest	26,642	[1]	26,642	[1]
Accumulated depletion	(6,348)		(6,007)
Mineral interest, net	20,294		20,635
Non-producing and developmental properties(B)	0		0
Total mining properties	73,442		74,330
Kensington [Member]
Mining Properties
Operational mining properties:	325,102		321,456
Accumulated depletion	(29,441)		(27,160)
Operational mining properties, net	295,661		294,296
Mineral interest	0	[1]	0	[1]
Accumulated depletion	0		0
Mineral interest, net	0		0
Non-producing and developmental properties(B)	0		0
Total mining properties	295,661		294,296
Rochester [Member]
Mining Properties
Operational mining properties:	113,094		112,826
Accumulated depletion	(98,391)		(97,834)
Operational mining properties, net	14,703		14,992
Mineral interest	0	[1]	0	[1]
Accumulated depletion	0		0
Mineral interest, net	0		0
Non-producing and developmental properties(B)	0		0
Total mining properties	14,703		14,992
Martha [Member]
Mining Properties
Operational mining properties:	13,226		12,643
Accumulated depletion	(10,807)		(10,373)
Operational mining properties, net	2,419		2,270
Mineral interest	0	[1]	0	[1]
Accumulated depletion	0		0
Mineral interest, net	0		0
Non-producing and developmental properties(B)	0		0
Total mining properties	2,419		2,270
Endeavor [Member]
Mining Properties
Operational mining properties:	0		0
Accumulated depletion	0		0
Operational mining properties, net	0		0
Mineral interest	44,033	[1]	44,033	[1]
Accumulated depletion	(11,678)		(10,034)
Mineral interest, net	32,355		33,999
Non-producing and developmental properties(B)	0		0
Total mining properties	32,355		33,999
Other Mining Properties [Member]
Mining Properties
Operational mining properties:	0		0
Accumulated depletion	0		0
Operational mining properties, net	0		0
Mineral interest	0	[1]	0	[1]
Accumulated depletion	0		0
Mineral interest, net	0		0
Non-producing and developmental properties(B)	142		142
Total mining properties	$ 142		$ 142

[1] See mineral interest explanations under operational mining properties for Palmarejo and San Bartolomé.