Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011		Dec. 31, 2011
Financial information relating to reporting segments
Sales of metal	$ 254,406		$ 231,090		$ 458,970		$ 430,714
Production costs applicable to sales	(131,823)		(77,102)		(224,377)		(169,576)
Depreciation and depletion	(61,024)		(57,641)		(113,616)		(107,682)
Gross profit (loss)	61,559		96,347		120,977		153,456
Exploration expense	6,305		4,077		12,872		6,839
Loss on impairment	4,813		0		4,813		0
OPERATING INCOME	41,574		79,339		85,761		117,881
Interest and other income	(3,221)		2,763		1,786		4,664
Interest expense	(7,557)		(9,268)		(14,227)		(18,573)
Fair value adjustments, net	16,039		(12,432)		(7,074)		(17,700)
Income tax benefit (expense)	(23,862)		(21,402)		(39,298)		(34,341)
Net income	22,973		38,611		26,948		51,075
Capital expenditures	32,238		25,764		63,885		41,681
Assets	3,233,510				3,233,510				3,264,441
Palmarejo [Member]
Financial information relating to reporting segments
Sales of metal	136,365		123,727		260,087		211,892
Production costs applicable to sales	(62,538)		(37,770)		(108,397)		(75,139)
Depreciation and depletion	(42,748)		(41,753)		(80,517)		(75,428)
Gross profit (loss)	31,079		44,204		71,173		61,325
Exploration expense	1,624		1,276		2,945		1,912
Loss on impairment					0
Other operating expenses	0		0		0		0
OPERATING INCOME	29,455		42,928		68,228		59,413
Interest and other income	(4,720)		539		(139)		1,828
Interest expense	(5,672)		(6,112)		(10,481)		(11,815)
Fair value adjustments, net	14,105		(13,731)		(11,505)		(20,041)
Income tax benefit (expense)	(11,967)		(6,286)		(15,511)		(10,062)
Net income	21,201		17,338		30,592		19,323
Capital expenditures	11,174	[1]	10,278	[1]	18,344	[1]	15,359	[1]
Assets	1,954,084	[2]	2,095,411	[2]	1,954,084	[2]	2,095,411	[2]
San Bartolome [Member]
Financial information relating to reporting segments
Sales of metal	53,383		55,598		94,759		101,919
Production costs applicable to sales	(22,773)		(14,126)		(36,381)		(28,244)
Depreciation and depletion	(4,070)		(5,182)		(8,289)		(10,325)
Gross profit (loss)	26,540		36,290		50,089		63,350
Exploration expense	(70)		31		0		35
Loss on impairment					0
Other operating expenses	25		70		30		108
OPERATING INCOME	26,585		36,189		50,059		63,207
Interest and other income	631		180		726		787
Interest expense	(36)		(2)		(36)		(36)
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	(10,889)		(12,109)		(18,578)		(22,146)
Net income	16,291		24,258		32,171		41,812
Capital expenditures	7,800	[1]	3,276	[1]	18,007	[1]	6,812	[1]
Assets	289,428	[2]	269,439	[2]	289,428	[2]	269,439	[2]
Kensington [Member]
Financial information relating to reporting segments
Sales of metal	21,124		26,012		31,500		74,122
Production costs applicable to sales	(16,106)		(12,844)		(33,197)		(45,764)
Depreciation and depletion	(9,719)		(9,890)		(16,324)		(19,255)
Gross profit (loss)	(4,701)		3,278		(18,021)		9,103
Exploration expense	274		320		496		366
Loss on impairment					0
Other operating expenses	16		116		35		136
OPERATING INCOME	(4,991)		2,842		(18,552)		8,601
Interest and other income	0		2		0		3
Interest expense	(901)		(1,360)		(1,793)		(2,607)
Fair value adjustments, net	2,187		2,374		1,636		1,676
Income tax benefit (expense)	0		0		0		(20)
Net income	(3,705)		3,858		(18,709)		7,653
Capital expenditures	9,324	[1]	7,365	[1]	20,202	[1]	12,734	[1]
Assets	518,611	[2]	507,531	[2]	518,611	[2]	507,531	[2]
Rochester [Member]
Financial information relating to reporting segments
Sales of metal	34,153		14,434		52,911		28,696
Production costs applicable to sales	(20,751)		(5,341)		(30,317)		(12,698)
Depreciation and depletion	(2,060)		(584)		(3,702)		(1,098)
Gross profit (loss)	11,342		8,509		18,892		14,900
Exploration expense	1,135		340		1,844		362
Loss on impairment					0
Other operating expenses	692		11,025		2,033		14,561
OPERATING INCOME	9,515		(2,856)		15,015		(23)
Interest and other income	239		5		288		51
Interest expense	(7)		0		(15)		0
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	0		0		0		0
Net income	9,747		(2,851)		15,288		28
Capital expenditures	2,946	[1]	4,201	[1]	5,585	[1]	5,869	[1]
Assets	94,677	[2]	35,606	[2]	94,677	[2]	35,606	[2]
Martha [Member]
Financial information relating to reporting segments
Sales of metal	4,149		4,769		7,767		4,455
Production costs applicable to sales	(7,102)		(3,749)		(10,795)		(3,359)
Depreciation and depletion	(704)		747		(1,300)		155
Gross profit (loss)	(3,657)		1,767		(4,328)		1,251
Exploration expense	2,763		1,527		6,174		2,823
Loss on impairment					4,813
Other operating expenses	81		0		279		0
OPERATING INCOME	(11,314)		240		(15,594)		(1,572)
Interest and other income	(494)		(179)		(570)		(489)
Interest expense	(1)		(68)		(1)		(413)
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	(28)		(410)		(239)		(369)
Net income	(11,837)		(417)		(16,404)		(2,843)
Capital expenditures	529	[1]	573	[1]	1,188	[1]	824	[1]
Assets	13,070	[2]	19,341	[2]	13,070	[2]	19,341	[2]
Endeavor [Member]
Financial information relating to reporting segments
Sales of metal	5,232		6,550		11,946		9,630
Production costs applicable to sales	(2,553)		(3,272)		(5,290)		(4,372)
Depreciation and depletion	(1,592)		(865)		(3,236)		(1,484)
Gross profit (loss)	1,087		2,413		3,420		3,774
Exploration expense	0		0		0		0
Loss on impairment					0
Other operating expenses	0		0		0		0
OPERATING INCOME	1,087		2,413		3,420		3,774
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)	0		(3)		0		(3)
Net income	1,087		2,410		3,420		3,771
Capital expenditures	0	[1]	0	[1]	0	[1]	0	[1]
Assets	33,228	[2]	40,760	[2]	33,228	[2]	40,760	[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	(131)		(114)		(248)		(247)
Gross profit (loss)	(131)		(114)		(248)		(247)
Exploration expense	579		583		1,413		1,341
Loss on impairment					0
Other operating expenses	8,053		1,720		15,154		13,931
OPERATING INCOME	(8,763)		(2,417)		(16,815)		(15,519)
Interest and other income	1,123		2,216		1,481		2,484
Interest expense	(940)		(1,726)		(1,901)		(3,702)
Fair value adjustments, net	(253)		(1,075)		2,795		665
Income tax benefit (expense)	(978)		(2,594)		(4,970)		(1,741)
Net income	(9,811)		(5,985)		(19,410)		(18,669)
Capital expenditures	465	[1]	71	[1]	559	[1]	83	[1]
Assets	16,654	[2]	16,201	[2]	16,654	[2]	16,201	[2]
Reportable Segment [Member]
Financial information relating to reporting segments
Sales of metal	254,406		231,090		458,970		430,714
Production costs applicable to sales	(131,823)		(77,102)		(224,377)		(169,576)
Depreciation and depletion	(61,024)		(57,641)		(113,616)		(107,682)
Gross profit (loss)	61,559		96,347		120,977		153,456
Exploration expense	6,305		4,077		12,872		6,839
Loss on impairment					4,813
Other operating expenses	8,867		12,931		17,531		28,736
OPERATING INCOME	41,574		79,339		85,761		117,881
Interest and other income	(3,221)		2,763		1,786		4,664
Interest expense	(7,557)		(9,268)		(14,227)		(18,573)
Fair value adjustments, net	16,039		(12,432)		(7,074)		(17,700)
Income tax benefit (expense)	(23,862)		(21,402)		(39,298)		(34,341)
Net income	22,973		38,611		26,948		51,075
Capital expenditures	32,238	[1]	25,764	[1]	63,885	[1]	41,681	[1]
Assets	2,919,752	[2]	2,984,289	[2]	2,919,752	[2]	2,984,289	[2]
Gold [Member]
Financial information relating to reporting segments
Sales of metal	93,700		72,300		159,000		159,400
Silver [Member]
Financial information relating to reporting segments
Sales of metal	$ 160,700		$ 158,800		$ 299,900		$ 271,300

[1] Balance represents cash flow amounts

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