INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE (Details 3) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended	3 Months Ended			8 Months Ended	9 Months Ended		12 Months Ended		1 Months Ended	3 Months Ended	1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 MSC	Jun. 30, 2013 MSC	Sep. 30, 2012 MSC	Sep. 30, 2012 MSC	Sep. 30, 2013 MSC	Sep. 30, 2012 MSC	Dec. 31, 2012 MSC	Jan. 24, 2012 MSC	Oct. 31, 2013 MSC Vend-in agreement Item	Dec. 31, 2013 MSC Vend-in agreement Subsequent event	Oct. 31, 2013 MSC Hochschild Item
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Sales percentage						100.00%		100.00%	100.00%	100.00%
Sales						$ 69,662,000		$ 116,299,000	$ 212,902,000	$ 182,031,000
Net income percentage						100.00%		100.00%	100.00%	100.00%
Net income						5,424,000		26,343,000	37,765,000	7,988,000
Ownership interest (as a percent)						49.00%				49.00%			49.00%
Net income on investment in MSC						2,658,000		12,908,000	18,505,000	3,914,000		25,301,000
Amortization of fair value increments						(618,000)		(1,668,000)	(3,537,000)	(3,662,000)	(3,537,000)	(4,466,000)
Income on investment in MSC, net of amortization	2,040,000	11,240,000	252,000	14,968,000		2,040,000		11,240,000	14,968,000	252,000
Current assets	50,920,000		50,920,000		91,918,000	120,200,000				120,200,000
Total assets	973,251,000		973,251,000		1,150,937,000	522,400,000				522,400,000
Current liabilities	11,392,000		11,392,000		25,195,000	56,400,000				56,400,000
Total liabilities	215,554,000		215,554,000		261,346,000	166,800,000				166,800,000
Impairment of investment in Minera Santa Cruz S.A.			95,878,000				95,900,000			95,878,000
Area of property transferred														48,900		82,700
Net smelter return royalty payable (as a percent)														2.00%
Carrying value of mining claims															53,200,000
Deferred tax liability related to mineral properties															17,300,000
Expected gain or loss to be recognized	$ 51,000	$ 1,233,000	$ (223,000)	$ 3,075,000	$ 3,075,000										$ 0