INVESTMENT IN MINERA SANTA CRUZ S.A. (“MSC”) - SAN JOSÉ MINE - Assets and Liabilities Associated with MSC (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Current assets	$ 56,972	$ 54,443
Total assets	479,990	475,085	$ 526,733
Current liabilities	17,287	22,039
Total liabilities	50,272	$ 56,793
MSC
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Current assets	94,000
Total assets	480,500
Current liabilities	36,300
Total liabilities	134,800
MSC | Current Period Values Excluding Fair Value Increments And Impairment Charge
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Current assets	93,000
Total assets	284,200
Current liabilities	47,100
Total liabilities	$ 83,700