Segment Reporting (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011
Financial information relating to reporting segments
Sales of metal	$ 230,593,000		$ 343,575,000		$ 689,563,000		$ 774,289,000
Production costs applicable to sales	(124,967,000)		(141,253,000)		(349,344,000)		(310,829,000)
Depreciation and depletion	(52,844,000)		(58,652,000)		(166,460,000)		(166,334,000)
Gross profit (loss)	52,782,000		143,670,000		173,759,000		297,126,000
Exploration expense	6,957,000		4,772,000		19,829,000		11,611,000
Loss on impairment	1,293,000		0		6,106,000		0
OPERATING INCOME	33,989,000		127,391,000		119,750,000		245,272,000
Interest and other income	12,664,000		(6,610,000)		14,450,000		(1,946,000)
Interest expense	(7,351,000)		(7,980,000)		(21,578,000)		(26,553,000)
Fair value adjustments, net	(37,648,000)		(53,351,000)		(44,722,000)		(71,051,000)
Income tax benefit (expense)	(17,475,000)		(27,606,000)		(56,773,000)		(61,947,000)
Net income	(15,821,000)		31,060,000		11,127,000		82,135,000
Capital expenditures	29,972,000		38,099,000		93,857,000		79,780,000
Assets	3,180,440,000				3,180,440,000				3,264,441,000
Palmarejo [Member]
Financial information relating to reporting segments
Sales of metal	102,642,000		166,875,000		362,729,000		378,767,000
Production costs applicable to sales	(48,672,000)		(64,112,000)		(157,070,000)		(139,251,000)
Depreciation and depletion	(34,007,000)		(41,182,000)		(114,525,000)		(116,610,000)
Gross profit (loss)	19,963,000		61,581,000		91,134,000		122,906,000
Exploration expense	2,288,000		2,200,000		5,232,000		4,112,000
Loss on impairment					0
Other operating expenses	0		225,000		0		225,000
OPERATING INCOME	17,675,000		59,156,000		85,902,000		118,569,000
Interest and other income	4,914,000		(6,278,000)		4,774,000		(4,450,000)
Interest expense	(4,401,000)		(5,270,000)		(14,883,000)		(17,085,000)
Fair value adjustments, net	(34,266,000)		(26,464,000)		(45,771,000)		(46,505,000)
Income tax benefit (expense)	5,495,000		(2,459,000)		(10,015,000)		(12,521,000)
Net income	(10,583,000)		18,685,000		20,007,000		38,008,000
Capital expenditures	11,321,000	[1]	9,528,000	[1]	29,665,000	[1]	24,887,000	[1]
Assets	1,926,695,000	[2]	2,050,108,000	[2]	1,926,695,000	[2]	2,050,108,000	[2]
San Bartolome [Member]
Financial information relating to reporting segments
Sales of metal	46,192,000		102,820,000		140,951,000		204,739,000
Production costs applicable to sales	(19,937,000)		(30,085,000)		(56,317,000)		(58,329,000)
Depreciation and depletion	(4,163,000)		(6,067,000)		(12,452,000)		(16,392,000)
Gross profit (loss)	22,092,000		66,668,000		72,182,000		130,018,000
Exploration expense	50,000		61,000		51,000		96,000
Loss on impairment					0
Other operating expenses	50,000		111,000		80,000		219,000
OPERATING INCOME	21,992,000		66,496,000		72,051,000		129,703,000
Interest and other income	8,353,000		(227,000)		9,079,000		560,000
Interest expense	(11,000)		(9,000)		(47,000)		(45,000)
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	(23,106,000)		(25,063,000)		(41,684,000)		(47,209,000)
Net income	7,228,000		41,197,000		39,399,000		83,009,000
Capital expenditures	4,406,000	[1]	4,418,000	[1]	22,413,000	[1]	11,230,000	[1]
Assets	299,041,000	[2]	265,488,000	[2]	299,041,000	[2]	265,488,000	[2]
Kensington [Member]
Financial information relating to reporting segments
Sales of metal	36,450,000		44,185,000		67,950,000		118,307,000
Production costs applicable to sales	(26,881,000)		(24,347,000)		(60,078,000)		(70,111,000)
Depreciation and depletion	(11,512,000)		(9,567,000)		(27,836,000)		(28,822,000)
Gross profit (loss)	(1,943,000)		10,271,000		(19,964,000)		19,374,000
Exploration expense	1,476,000		308,000		1,971,000		674,000
Loss on impairment					0
Other operating expenses	39,000		88,000		75,000		224,000
OPERATING INCOME	(3,458,000)		9,875,000		(22,010,000)		18,476,000
Interest and other income	0		1,000		1,000		4,000
Interest expense	(1,834,000)		(1,115,000)		(3,627,000)		(3,722,000)
Fair value adjustments, net	(4,283,000)		(22,244,000)		(2,647,000)		(20,568,000)
Income tax benefit (expense)	0		(1,000)		0		(21,000)
Net income	(9,575,000)		(13,484,000)		(28,283,000)		(5,831,000)
Capital expenditures	9,034,000	[1]	9,230,000	[1]	29,235,000	[1]	21,964,000	[1]
Assets	520,619,000	[2]	515,335,000	[2]	520,619,000	[2]	515,335,000	[2]
Rochester [Member]
Financial information relating to reporting segments
Sales of metal	36,244,000		17,453,000		89,156,000		46,149,000
Production costs applicable to sales	(21,014,000)		(11,356,000)		(51,331,000)		(24,054,000)
Depreciation and depletion	(2,061,000)		(573,000)		(5,763,000)		(1,671,000)
Gross profit (loss)	13,169,000		5,524,000		32,062,000		20,424,000
Exploration expense	1,158,000		242,000		3,003,000		604,000
Loss on impairment					0
Other operating expenses	1,109,000		3,158,000		3,142,000		17,719,000
OPERATING INCOME	10,902,000		2,124,000		25,917,000		2,101,000
Interest and other income	59,000		7,000		347,000		58,000
Interest expense	(6,000)		(14,000)		(21,000)		(14,000)
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	0		0		0		0
Net income	10,955,000		2,117,000		26,243,000		2,145,000
Capital expenditures	4,777,000	[1]	13,559,000	[1]	10,362,000	[1]	19,428,000	[1]
Assets	104,066,000	[2]	55,734,000	[2]	104,066,000	[2]	55,734,000	[2]
Martha [Member]
Financial information relating to reporting segments
Sales of metal	4,933,000		6,037,000		12,700,000		10,492,000
Production costs applicable to sales	(6,481,000)		(8,143,000)		(17,276,000)		(11,502,000)
Depreciation and depletion	(32,000)		(237,000)		(1,332,000)		(82,000)
Gross profit (loss)	(1,580,000)		(2,343,000)		(5,908,000)		(1,092,000)
Exploration expense	1,217,000		1,477,000		7,391,000		4,300,000
Loss on impairment	1,293,000				6,106,000
Other operating expenses	133,000		150,000		411,000		150,000
OPERATING INCOME	(4,223,000)		(3,970,000)		(19,816,000)		(5,542,000)
Interest and other income	(342,000)		(99,000)		(912,000)		(588,000)
Interest expense	(2,000)		(35,000)		(3,000)		(448,000)
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	1,233,000		(173,000)		993,000		(542,000)
Net income	(3,334,000)		(4,277,000)		(19,738,000)		(7,120,000)
Capital expenditures	6,000	[1]	1,130,000	[1]	1,194,000	[1]	1,954,000	[1]
Assets	11,339,000	[2]	19,537,000	[2]	11,339,000	[2]	19,537,000	[2]
Endeavor [Member]
Financial information relating to reporting segments
Sales of metal	4,132,000		6,205,000		16,077,000		15,835,000
Production costs applicable to sales	(1,982,000)		(3,210,000)		(7,272,000)		(7,582,000)
Depreciation and depletion	(898,000)		(914,000)		(4,134,000)		(2,398,000)
Gross profit (loss)	1,252,000		2,081,000		4,671,000		5,855,000
Exploration expense	0		0		0		0
Loss on impairment					0
Other operating expenses	0		(1,000)		0		(1,000)
OPERATING INCOME	1,252,000		2,082,000		4,671,000		5,856,000
Interest and other income	0		0		0		0
Interest expense	0		0		0		0
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	(202,000)		107,000		(202,000)		104,000
Net income	1,050,000		2,189,000		4,469,000		5,960,000
Capital expenditures	0	[1]	0	[1]	0	[1]	0	[1]
Assets	32,619,000	[2]	37,546,000	[2]	32,619,000	[2]	37,546,000	[2]
Other Mining Properties [Member]
Financial information relating to reporting segments
Sales of metal	0		0		0		0
Production costs applicable to sales	0		0		0		0
Depreciation and depletion	(171,000)		(112,000)		(418,000)		(359,000)
Gross profit (loss)	(171,000)		(112,000)		(418,000)		(359,000)
Exploration expense	768,000		484,000		2,181,000		1,825,000
Loss on impairment					0
Other operating expenses	9,212,000		7,776,000		24,366,000		21,707,000
OPERATING INCOME	(10,151,000)		(8,372,000)		(26,965,000)		(23,891,000)
Interest and other income	(320,000)		(14,000)		1,161,000		2,470,000
Interest expense	(1,097,000)		(1,537,000)		(2,997,000)		(5,239,000)
Fair value adjustments, net	901,000		(4,643,000)		3,696,000		(3,978,000)
Income tax benefit (expense)	(895,000)		(17,000)		(5,865,000)		(1,758,000)
Net income	(11,562,000)		(15,367,000)		(30,970,000)		(34,036,000)
Capital expenditures	428,000	[1]	234,000	[1]	988,000	[1]	317,000	[1]
Assets	18,613,000	[2]	17,693,000	[2]	18,613,000	[2]	17,693,000	[2]
Reportable Segment [Member]
Financial information relating to reporting segments
Sales of metal	230,593,000		343,575,000		689,563,000		774,289,000
Production costs applicable to sales	(124,967,000)		(141,253,000)		(349,344,000)		(310,829,000)
Depreciation and depletion	(52,844,000)		(58,652,000)		(166,460,000)		(166,334,000)
Gross profit (loss)	52,782,000		143,670,000		173,759,000		297,126,000
Exploration expense	6,957,000		4,772,000		19,829,000		11,611,000
Loss on impairment	1,293,000				6,106,000
Other operating expenses	10,543,000		11,507,000		28,074,000		40,243,000
OPERATING INCOME	33,989,000		127,391,000		119,750,000		245,272,000
Interest and other income	12,664,000		(6,610,000)		14,450,000		(1,946,000)
Interest expense	(7,351,000)		(7,980,000)		(21,578,000)		(26,553,000)
Fair value adjustments, net	(37,648,000)		(53,351,000)		(44,722,000)		(71,051,000)
Income tax benefit (expense)	(17,475,000)		(27,606,000)		(56,773,000)		(61,947,000)
Net income	(15,821,000)		31,060,000		11,127,000		82,135,000
Capital expenditures	29,972,000	[1]	38,099,000	[1]	93,857,000	[1]	79,780,000	[1]
Assets	$ 2,912,992,000	[2]	$ 2,961,441,000	[2]	$ 2,912,992,000	[2]	$ 2,961,441,000	[2]

[1] Balance represents cash flow amounts

[2] Segment assets consist of receivables, prepaids, inventories, property, plant and equipment, and mining properties