BUSINESS SEGMENTS INFORMATION (Customers and Labor Matters) (Details) - USD ($) $ in Millions	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015
Major Customer and Labor Matters [Line Items]
Segment Reporting, Disclosure of Major Customers									.12
Revenues	$ 3,911	$ 3,153	$ 3,546	$ 3,792	$ 3,684	$ 4,908	$ 5,168	$ 4,868		$ 14,402	$ 18,628	$ 16,403
Affiliated Entity | Noncontrolling Interest Owners Of South America Mining Operations
Major Customer and Labor Matters [Line Items]
Revenues										1,000	1,200	1,100	$ 1,000
Affiliated Entity | PT Smelting
Major Customer and Labor Matters [Line Items]
Revenues										1,900	2,200	2,000
Indonesia
Major Customer and Labor Matters [Line Items]
Revenues										$ 1,894	$ 2,226	$ 2,023