Mining Properties (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Mining Properties
Operational mining properties:	$ 679,224		$ 649,905
Accumulated depletion	(242,969)		(203,416)
Operational mining properties, net	436,255		446,489
Mineral interest	1,729,064	[1]	1,729,064	[1]
Accumulated depletion	(242,210)		(174,668)
Mineral interest, net	1,486,854		1,554,396
Non-producing and developmental properties(B)	142		142
Total mining properties	1,923,251		2,001,027
Palmarejo [Member]
Mining Properties
Operational mining properties:	151,373		134,296
Accumulated depletion	(74,974)		(53,060)
Operational mining properties, net	76,399		81,236
Mineral interest	1,658,389	[1]	1,658,389	[1]
Accumulated depletion	(221,027)		(158,627)
Mineral interest, net	1,437,362		1,499,762
Non-producing and developmental properties(B)	0		0
Total mining properties	1,513,761		1,580,998
San Bartolome [Member]
Mining Properties
Operational mining properties:	70,099		68,684
Accumulated depletion	(17,602)		(14,989)
Operational mining properties, net	52,497		53,695
Mineral interest	26,642	[1]	26,642	[1]
Accumulated depletion	(7,015)		(6,007)
Mineral interest, net	19,627		20,635
Non-producing and developmental properties(B)	0		0
Total mining properties	72,124		74,330
Kensington [Member]
Mining Properties
Operational mining properties:	331,697		321,456
Accumulated depletion	(39,204)		(27,160)
Operational mining properties, net	292,493		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	292,493		294,296
Rochester [Member]
Mining Properties
Operational mining properties:	114,639		112,826
Accumulated depletion	(99,773)		(97,834)
Operational mining properties, net	14,866		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	14,866		14,992
Martha [Member]
Mining Properties
Operational mining properties:	11,416		12,643
Accumulated depletion	(11,416)		(10,373)
Operational mining properties, net	0		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	0		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	(14,168)		(10,034)
Mineral interest, net	29,865		33,999
Non-producing and developmental properties(B)	0		0
Total mining properties	29,865		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

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