CONTINGENCIES (Tax Matters by Tax Year) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Income Tax Examination [Line Items]
Income Taxes Receivable, Noncurrent	$ 260	$ 445
SUNAT | Cerro Verde
Income Tax Examination [Line Items]
Income Taxes Receivable, Noncurrent	386
Tax Assessment	257
Penalty and Interest Assessment	351
Total	608
SUNAT | 2003 to 2008 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	56
Penalty and Interest Assessment	130
Total	186
SUNAT | 2009 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	57
Penalty and Interest Assessment	51
Total	108
SUNAT | 2010 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	63
Penalty and Interest Assessment	105
Total	168
SUNAT | 2011 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	49
Penalty and Interest Assessment	65
Total	114
SUNAT | 2014 to 2018 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	32
Penalty and Interest Assessment	0
Total	32
Indonesian Tax Authority | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	1,016
Interest Assessment	288
Total	1,304
Indonesian Tax Authority | 2005 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	73
Interest Assessment	35
Total	108
Indonesian Tax Authority | 2007 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	47
Interest Assessment	23
Total	70
Indonesian Tax Authority | 2009, 2010 to 2011 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	55
Interest Assessment	37
Total	92
Indonesian Tax Authority | 2012 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	124
Interest Assessment	0
Total	124
Indonesian Tax Authority | 2013 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	154
Interest Assessment	74
Total	228
Indonesian Tax Authority | 2014 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	139
Interest Assessment	6
Total	145
Indonesian Tax Authority | 2015 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	158
Interest Assessment	0
Total	158
Indonesian Tax Authority | 2016 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	266
Interest Assessment	113
Total	379
PT-FI
Income Tax Examination [Line Items]
Income Taxes Receivable, Noncurrent	$ 493	$ 417