Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended							12 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Financial information relating to reporting segments
Sales of metal	$ 343,575	$ 231,090	$ 199,624	$ 207,586	$ 118,564	$ 101,018	$ 88,289	$ 246,911	$ 1,021,200	$ 515,457	$ 300,361
Production costs applicable to sales	(141,253)	(77,102)	(92,474)	(87,625)	(60,402)	(58,590)	(51,019)	(109,127)	(419,956)	(257,636)	(191,311)
Depreciation and depletion	(58,652)	(57,641)	(50,041)	(45,062)	(37,801)	(29,983)	(28,773)	(55,829)	(224,500)	(141,619)	(81,376)
Gross profit (loss)									376,744	116,202	27,674
Exploration expense	4,772	4,077	2,762	4,764	3,804	3,161	2,520	7,517	19,128	14,249	13,056
Other operating expenses	(11,507)	(12,931)	(15,805)	(3,417)	(6,045)	(7,424)	(8,180)	(10,577)
Interest and other income									(6,610)	771	1,648
OPERATING INCOME (LOSS)									306,796	74,900	(8,920)
Interest expense									34,774	30,942	18,102
Loss on debt extinguishment									(5,526)	(20,300)	31,528
Fair value adjustments, net									(52,050)	(117,094)	(82,227)
Income tax benefit (expense)									(114,337)	9,481	33,071
Income (loss) from continuing operations	31,060	38,611	12,464	(5,078)	(23,259)	(44,801)	(10,046)	29,311	93,499	(83,184)	(43,002)
Loss from discontinued operations	0	0	0		631	(5,943)	(2,812)			(6,029)	(9,601)
Income (loss) on sale of net assets of discontinued operations, net of taxes of $0.0 million for 2011 and $0.0 million for 2010										(2,095)	25,537
Net income (loss)	31,060	38,611	12,464	(5,078)	(22,628)	(50,744)	(12,858)	29,311	93,499	(91,308)	(27,066)
Segment assets				3,157,527				3,264,441	3,264,441	3,157,527	3,054,035
Capital expenditures	38,099	25,764	15,918	26,555	36,783	45,467	47,189	40,207	119,988	155,994	218,235
Palmarejo [Member]
Financial information relating to reporting segments
Sales of metal									513,097	230,024	90,560
Production costs applicable to sales									(186,201)	(127,658)	(66,262)
Depreciation and depletion									(159,264)	(91,505)	(52,042)
Gross profit (loss)									167,632	10,861	(27,745)
Exploration expense									6,863	4,658	5,615
Other operating expenses									949	352	968
Interest and other income									(9,099)	914	1,075
OPERATING INCOME (LOSS)									159,820	5,851	(34,328)
Interest expense									23,453	21,567	14,213
Fair value adjustments, net									(40,046)	(98,707)	(78,148)
Income tax benefit (expense)									(28,023)	16,901	45,063
Income (loss) from continuing operations									59,199	(96,608)	(80,551)
Net income (loss)									59,199	(96,608)	(80,551)
Segment assets				2,119,367				2,029,769	2,029,769	2,119,367	2,129,024
Capital expenditures									36,976	54,226	162,697
San Bartolome [Member]
Financial information relating to reporting segments
Sales of metal									267,502	142,989	113,701
Production costs applicable to sales									(79,679)	(60,023)	(80,878)
Depreciation and depletion									(22,410)	(19,650)	(18,510)
Gross profit (loss)									165,413	63,316	14,313
Exploration expense									248	9	34
Other operating expenses									(342)
Interest and other income									156	(373)	1,075
OPERATING INCOME (LOSS)									164,823	63,307	14,279
Interest expense									(45)	(325)	(125)
Income tax benefit (expense)									(59,867)	(21,655)	(8,894)
Income (loss) from continuing operations									105,067	40,954	6,335
Net income (loss)									105,067	40,954	6,335
Segment assets				260,653				276,423	276,423	260,653	276,926
Capital expenditures									17,731	6,159	11,091
Kensington [Member]
Financial information relating to reporting segments
Sales of metal									151,186	23,628
Production costs applicable to sales									(101,672)	(14,043)
Depreciation and depletion									(35,839)	(17,487)
Gross profit (loss)									13,675	(7,902)
Exploration expense									1,102	659	297
Other operating expenses									317	170	39
Interest and other income									4	(26)	3
OPERATING INCOME (LOSS)									12,256	(8,731)	(336)
Interest expense									4,889	(1,591)	(16)
Fair value adjustments, net									(8,438)	(13,783)	(965)
Income tax benefit (expense)									(31)	(8)	5
Income (loss) from continuing operations									(1,098)	(24,139)	(1,309)
Net income (loss)									(1,098)	(24,139)	(1,309)
Segment assets				512,401				507,891	507,891	512,401	397,457
Capital expenditures									34,013	92,730	41,289
Rochester [Member]
Financial information relating to reporting segments
Sales of metal									57,331	54,323	45,472
Production costs applicable to sales									(28,257)	(24,760)	(24,206)
Depreciation and depletion									(2,824)	(1,890)	(1,852)
Gross profit (loss)									26,250	27,673	19,414
Exploration expense									1,989	190
Other operating expenses									19,931	1,544	912
Interest and other income									57	681	(168)
OPERATING INCOME (LOSS)									4,330	25,939	18,502
Interest expense									(21)
Income (loss) from continuing operations									4,366	26,620	18,334
Net income (loss)									4,366	26,620	18,334
Segment assets				29,734				76,892	76,892	29,734	31,232
Capital expenditures									27,217	2,349	310
Martha [Member]
Financial information relating to reporting segments
Sales of metal									13,347	53,875	44,820
Production costs applicable to sales									(15,513)	(27,040)	(17,896)
Depreciation and depletion									(556)	(8,525)	(7,410)
Gross profit (loss)									(2,722)	18,310	19,514
Exploration expense									6,367	5,791	3,119
Other operating expenses									(156)
Interest and other income									(544)	(3,794)	(1,953)
OPERATING INCOME (LOSS)									(9,245)	12,519	16,395
Interest expense									(458)	(90)	(401)
Income tax benefit (expense)									(1,219)	(8,523)	(6,284)
Income (loss) from continuing operations									(11,466)	(68)	7,757
Net income (loss)									(11,466)	(68)	7,757
Segment assets				21,290				19,717	19,717	21,290	33,024
Capital expenditures									3,426	100	1,575
Endeavor [Member]
Financial information relating to reporting segments
Sales of metal									18,737	10,618	5,808
Production costs applicable to sales									(8,634)	(4,112)	(2,069)
Depreciation and depletion									(3,148)	(1,989)	(1,269)
Gross profit (loss)									6,955	4,517	2,470
Other operating expenses									1
OPERATING INCOME (LOSS)									6,956	4,517	2,470
Income (loss) from continuing operations									6,956	4,517	2,470
Net income (loss)									4,956	4,517	2,470
Segment assets				39,530				35,686	35,686	39,530	39,852
Other [Member]
Financial information relating to reporting segments
Depreciation and depletion									(459)	(573)	(292)
Gross profit (loss)									(459)	(573)	(292)
Exploration expense									2,559	2,942	3,991
Other operating expenses									29,126	24,987	21,619
Interest and other income									2,815	3,549	1,616
OPERATING INCOME (LOSS)									(32,144)	(28,502)	(25,902)
Interest expense									5,908	7,369	3,347
Loss on debt extinguishment									(5,526)	(20,300)	31,528
Fair value adjustments, net									(3,566)	(4,604)	(3,114)
Income tax benefit (expense)									(25,197)	22,766	3,181
Income (loss) from continuing operations									(69,526)	34,460	3,962
Loss from discontinued operations									0	(6,029)	(9,601)
Income (loss) on sale of net assets of discontinued operations, net of taxes of $0.0 million for 2011 and $0.0 million for 2010										(2,095)	25,537
Net income (loss)									(69,526)	(42,584)	19,898
Segment assets				17,414				16,792	16,792	17,414	46,948
Capital expenditures									625	430	1,273
Reportable Segment [Member]
Financial information relating to reporting segments
Sales of metal									1,021,200	515,457	300,361
Production costs applicable to sales									(419,956)	(257,636)	(191,311)
Depreciation and depletion									(224,500)	(141,619)	(81,376)
Exploration expense									19,128	14,249	13,056
Other operating expenses									50,820	27,053	23,538
Interest and other income									(6,610)	771	1,648
Interest expense									34,774	30,942	18,102
Loss on debt extinguishment									(5,526)	(20,300)	31,528
Fair value adjustments, net									(52,050)	(117,094)	(82,227)
Income tax benefit (expense)									(114,337)	9,481	33,071
Income (loss) from continuing operations									93,499	(83,184)	(43,002)
Loss from discontinued operations									0	(6,029)	(9,601)
Income (loss) on sale of net assets of discontinued operations, net of taxes of $0.0 million for 2011 and $0.0 million for 2010										(2,095)	25,537
Net income (loss)									93,499	(91,308)	27,066
Segment assets				3,000,389				2,963,130	2,963,130	3,000,389	2,954,463
Capital expenditures									$ 119,988	$ 155,994	$ 218,235