CONTINGENCIES (Tax Matters by Tax Year) (Details) - USD ($) $ in Millions	12 Months Ended			21 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 21, 2018
Income Tax Examination [Line Items]
Income Taxes Receivable, Noncurrent	$ 290	$ 260
Export Duties Expense	$ 221	180	$ 115
PT-FI
Income Tax Examination [Line Items]
Progressive export duty on copper concentrates, higher threshold, percent	5.00%			7.50%
Export Duties Expense	$ 66	180	$ 115
SUNAT | Cerro Verde
Income Tax Examination [Line Items]
Income Taxes Receivable, Noncurrent	397
Tax Assessment	312
Penalty and Interest Assessment	357
Total	669
SUNAT | 2003 to 2008 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	53
Penalty and Interest Assessment	122
Total	175
SUNAT | 2009 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	56
Penalty and Interest Assessment	52
Total	108
SUNAT | 2010 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	63
Penalty and Interest Assessment	107
Total	170
SUNAT | 2011 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	49
Penalty and Interest Assessment	65
Total	114
SUNAT | 2012 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	52
Penalty and Interest Assessment	11
Total	63
SUNAT | 2014 to 2019 | Cerro Verde
Income Tax Examination [Line Items]
Tax Assessment	39
Penalty and Interest Assessment	0
Total	39
Indonesia Tax Authority | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	1,009
Interest Assessment	282
Total	1,291
Indonesia Tax Authority | 2012 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	124
Interest Assessment	0
Total	124
Indonesia Tax Authority | 2005 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	73
Interest Assessment	35
Total	108
Indonesia Tax Authority | 2007 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	48
Interest Assessment	23
Total	71
Indonesia Tax Authority | 2009, 2010 to 2011 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	55
Interest Assessment	31
Total	86
Indonesia Tax Authority | 2013 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	154
Interest Assessment	74
Total	228
Indonesia Tax Authority | 2014 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	139
Interest Assessment	6
Total	145
Indonesia Tax Authority | 2015 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	159
Interest Assessment	0
Total	159
Indonesia Tax Authority | 2016 | PT-FI
Income Tax Examination [Line Items]
Tax Assessment	257
Interest Assessment	113
Total	370
PT-FI
Income Tax Examination [Line Items]
Income Taxes Receivable, Noncurrent	$ 178	$ 493