Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012		Dec. 31, 2012
Financial information relating to reporting segments
Sales of metal	$ 204,525		$ 254,406		$ 376,322		$ 458,970
Production costs applicable to sales	(142,924)		(131,823)		(231,708)		(224,377)
Depreciation and depletion	(57,653)		(61,024)		(108,089)		(113,616)
Gross profit	3,948		61,559		36,525		120,977
Exploration expense	6,774		6,305		13,615		12,872
Loss on impairment	86		4,813		205		4,813
OPERATING INCOME	(50,957)		41,574		(40,052)		85,761
Interest and other income	419		(3,221)		4,275		1,786
Interest expense	(10,930)		(7,557)		(20,662)		(14,227)
Fair value adjustments, net	66,754		16,039		84,550		(7,074)
Income tax benefit (expense)	(23,134)		(23,862)		(33,654)		(39,298)
Net income	(35,040)		22,973		(22,770)		26,948
Capital expenditures	27,201		32,238		40,028		63,885
Assets	3,666,716				3,666,716				3,221,401
Palmarejo [Member]
Financial information relating to reporting segments
Sales of metal	86,217		136,365		143,643		260,087
Production costs applicable to sales	(55,218)		(62,538)		(81,937)		(108,397)
Depreciation and depletion	(35,557)		(42,748)		(64,507)		(80,517)
Gross profit	(4,558)		31,079		(2,801)		71,173
Exploration expense	3,189		1,624		5,170		2,945
Loss on impairment	0
Other operating expenses	0		0		0		0
OPERATING INCOME	(7,747)		29,455		(7,971)		68,228
Interest and other income	(428)		(4,720)		1,514		(139)
Interest expense	(4,190)		(5,672)		(7,928)		(10,481)
Fair value adjustments, net	61,066		14,105		75,494		(11,505)
Income tax benefit (expense)	(17,282)		(11,967)		(20,816)		(15,511)
Net income	31,419		21,201		40,293		30,592
Capital expenditures	9,166	[1]	11,174	[1]	14,480	[1]	18,344	[1]
Assets	1,860,240	[2]	1,954,084	[2]	1,860,240	[2]	1,954,084	[2]
San Bartolome [Member]
Financial information relating to reporting segments
Sales of metal	49,236		53,383		82,377		94,759
Production costs applicable to sales	(32,815)		(22,773)		(48,494)		(36,381)
Depreciation and depletion	(4,941)		(4,070)		(9,696)		(8,289)
Gross profit	11,480		26,540		24,187		50,089
Exploration expense	27		(70)		79		0
Loss on impairment	0
Other operating expenses	0		25		3,722		30
OPERATING INCOME	11,453		26,585		20,386		50,059
Interest and other income	683		631		1,288		726
Interest expense	(14)		(36)		(46)		(36)
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	(4,506)		(10,889)		(8,834)		(18,578)
Net income	7,616		16,291		12,794		32,171
Capital expenditures	3,159	[1]	7,800	[1]	3,616	[1]	18,007	[1]
Assets	286,325	[2]	289,428	[2]	286,325	[2]	289,428	[2]
Kensington [Member]
Financial information relating to reporting segments
Sales of metal	30,851		21,124		70,126		31,500
Production costs applicable to sales	(30,154)		(16,106)		(53,718)		(33,197)
Depreciation and depletion	(13,261)		(9,719)		(26,647)		(16,324)
Gross profit	(12,564)		(4,701)		(10,239)		(18,021)
Exploration expense	563		274		1,235		496
Loss on impairment	0
Other operating expenses	134		16		210		35
OPERATING INCOME	(13,261)		(4,991)		(11,684)		(18,552)
Interest and other income	150		0		281		0
Interest expense	(95)		(901)		(354)		(1,793)
Fair value adjustments, net	6,350		2,187		10,577		1,636
Income tax benefit (expense)	0		0		(1)		0
Net income	(6,856)		(3,705)		(1,181)		(18,709)
Capital expenditures	7,406	[1]	9,324	[1]	10,736	[1]	20,202	[1]
Assets	485,215	[2]	518,611	[2]	485,215	[2]	518,611	[2]
Rochester [Member]
Financial information relating to reporting segments
Sales of metal	34,903		34,153		74,377		52,911
Production costs applicable to sales	(23,054)		(20,751)		(44,557)		(30,317)
Depreciation and depletion	(2,324)		(2,060)		(4,505)		(3,702)
Gross profit	9,525		11,342		25,315		18,892
Exploration expense	512		1,135		996		1,844
Loss on impairment	0
Other operating expenses	34,177		692		34,321		2,033
OPERATING INCOME	(25,164)		9,515		(10,002)		15,015
Interest and other income	0		239		57		288
Interest expense	(5)		(7)		(11)		(15)
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	0		0		0		0
Net income	(25,169)		9,747		(9,956)		15,288
Capital expenditures	6,596	[1]	2,946	[1]	9,894	[1]	5,585	[1]
Assets	122,917	[2]	94,677	[2]	122,917	[2]	94,677	[2]
Martha [Member]
Financial information relating to reporting segments
Sales of metal	(161)		4,149		(662)		7,767
Production costs applicable to sales	0		(7,102)		0		(10,795)
Depreciation and depletion	(113)		(704)		(229)		(1,300)
Gross profit	(274)		(3,657)		(891)		(4,328)
Exploration expense	603		2,763		1,587		6,174
Loss on impairment	86		4,813		205		4,813
Other operating expenses	861		81		1,906		279
OPERATING INCOME	(1,824)		(11,314)		(4,589)		(15,594)
Interest and other income	(177)		(494)		746		(570)
Interest expense	(1)		(1)		0		(1)
Fair value adjustments, net	0		0		0		0
Income tax benefit (expense)	(117)		(28)		(44)		(239)
Net income	(2,119)		(11,837)		(3,887)		(16,404)
Capital expenditures	10	[1]	529	[1]	10	[1]	1,188	[1]
Assets	6,757	[2]	13,070	[2]	6,757	[2]	13,070	[2]
Endeavor [Member]
Financial information relating to reporting segments
Sales of metal	3,479		5,232		6,461		11,946
Production costs applicable to sales	(1,683)		(2,553)		(3,003)		(5,290)
Depreciation and depletion	(1,220)		(1,592)		(2,044)		(3,236)
Gross profit	576		1,087		1,414		3,420
Exploration expense	0		0		0		0
Loss on impairment	0
Other operating expenses	0		0		0		0
OPERATING INCOME	576		1,087		1,414		3,420
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)	85		0		84		0
Net income	661		1,087		1,498		3,420
Capital expenditures	0	[1]	0	[1]	0	[1]	0	[1]
Assets	30,226	[2]	33,228	[2]	30,226	[2]	33,228	[2]
Joaquin [Member]
Financial information relating to reporting segments
Sales of metal	0
Production costs applicable to sales	0				0
Depreciation and depletion	(2)				(2)
Gross profit	(2)				(2)
Exploration expense	690				690
Other operating expenses	0				0
OPERATING INCOME	(692)				(692)
Interest and other income	(11)				(11)
Interest expense	0				0
Fair value adjustments, net	0				0
Income tax benefit (expense)	0				0
Net income	(703)				(703)
Capital expenditures	735	[1]			735	[1]
Assets	409,458	[2]			409,458	[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		1		0
Depreciation and depletion	(235)		(131)		(459)		(248)
Gross profit	(235)		(131)		(458)		(248)
Exploration expense	1,190		579		3,858		1,413
Other operating expenses	12,873		8,053		22,598		15,154
OPERATING INCOME	(14,298)		(8,763)		(26,914)		(16,815)
Interest and other income	(16,990)		1,123		(16,827)		1,481
Interest expense	(6,625)		(940)		(12,323)		(1,901)
Fair value adjustments, net	(662)		(253)		(1,521)		2,795
Income tax benefit (expense)	(1,314)		(978)		(4,043)		(4,970)
Net income	(39,889)		(9,811)		(61,628)		(19,410)
Capital expenditures	129	[1]	465	[1]	557	[1]	559	[1]
Assets	103,464	[2]	16,654	[2]	103,464	[2]	16,654	[2]
Reportable Segment [Member]
Financial information relating to reporting segments
Sales of metal	204,525		254,406		376,322		458,970
Production costs applicable to sales	(142,924)		(131,823)		(231,708)		(224,377)
Depreciation and depletion	(57,653)		(61,024)		(108,089)		(113,616)
Gross profit	3,948		61,559		36,525		120,977
Exploration expense	6,774		6,305		13,615		12,872
Loss on impairment	86				205		4,813
Other operating expenses	48,045		8,867		62,757		17,531
OPERATING INCOME	(50,957)		41,574		(40,052)		85,761
Interest and other income	(16,773)		(3,221)		(12,952)		1,786
Interest expense	(10,930)		(7,557)		(20,662)		(14,227)
Fair value adjustments, net	66,754		16,039		84,550		(7,074)
Income tax benefit (expense)	(23,134)		(23,862)		(33,654)		(39,298)
Net income	(35,040)		22,973		(22,770)		26,948
Capital expenditures	27,201	[1]	32,238	[1]	40,028	[1]	63,885	[1]
Assets	$ 3,304,602	[2]	$ 2,919,752	[2]	$ 3,304,602	[2]	$ 2,919,752	[2]

[1] Balance represents cash flow amounts Three months ended June 30, 2012PalmarejoMine San BartoloméMine KensingtonMine RochesterMine MarthaMine EndeavorMine Other TotalSales of metals$136,365 $53,383 $21,124 $34,153 $4,149 $5,232 $— $254,406Productions costs applicable to sales(62,538) (22,773) (16,106) (20,751) (7,102) (2,553) — (131,823)Depreciation and depletion(42,748) (4,070) (9,719) (2,060) (704) (1,592) (131) (61,024)Gross profit31,079 26,540 (4,701) 11,342 (3,657) 1,087 (131) 61,559Exploration expense1,624 (70) 274 1,135 2,763 — 579 6,305Loss on impairment— — — — 4,813 — — Other operating expenses— 25 16 692 81 — 8,053 8,867OPERATING INCOME29,455 26,585 (4,991) 9,515 (11,314) 1,087 (8,763) 41,574Interest and other income, net(4,720) 631 — 239 (494) — 1,123 (3,221)Interest expense(5,672) (36) (901) (7) (1) — (940) (7,557)Fair value adjustments, net14,105 — 2,187 — — — (253) 16,039Income tax benefit (expense)(11,967) (10,889) — — (28) — (978) (23,862)Net income$21,201 $16,291 $(3,705) $9,747 $(11,837) $1,087 $(9,811) $22,973Segment assets (A)$1,954,084 $289,428 $518,611 $94,677 $13,070 $33,228 $16,654 $2,919,752Capital expenditures (B)$11,174 $7,800 $9,324 $2,946 $529 $— $465 $32,238

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