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Percent of net assets at close of period. For schedules of investments that are categorized, each category has a percent of net assets for the aggregated value of the Investments in the category.

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DISPOSITIONS AND ACQUISITIONS (Morenci) (Details) - USD ($) $ in Millions			12 Months Ended
	Dec. 21, 2018	May 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture, net	$ 350
Net gain (loss) on sales of assets			$ 208	$ 81	$ 649
Morenci
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage		85.00%
Proceeds from divestiture, net		$ 1,000
Net gain (loss) on sales of assets		$ 576
Morenci \| SMM Morenci Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage			13.00%
Morenci \| Sumitomo Metal Mining Co., Ltd.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage		15.00%
Morenci
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage			72.00%
Morenci \| SMM Morenci Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage		13.00%
Morenci \| Sumitomo Metal Mining Co., Ltd.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage			15.00%