CONTINGENCIES (Environmental Obligations) (Details) $ in Millions		12 Months Ended
	Jan. 17, 2017 USD ($) divisions site	Dec. 31, 2020 USD ($) project state	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Site Contingency [Line Items]
Number of remediation projects | project		100
Number of US States with remediation projects | state		24
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year		$ 1,561	$ 1,511	$ 1,439
Accretion Expense		102	102	100
Additionsb		38	23	56
Reductions		(58)	(1)	0
Spending		(59)	(74)	(84)
Balance at end of year		1,584	1,561	1,511
Less current portion		(83)	(106)	(132)
Long-term portion		1,501	$ 1,455	$ 1,379
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
2020		83
2021		95
2022		100
2023		100
2024		100
Thereafter		3,200
Estimated environmental obligations on a discounted basis		1,500
Estimated environmental obligations on an undiscounted and unescalated		3,700
Environmental Loss Contingency, Number of Uranium Sites on Tribal Lands | divisions	94
Remediation work related to Uranium mines, amount to be contributed by the U.S. Government	$ 335
Uranium mine remediation work, program term, in years	20 years
Reduction of environmental obligation due to deceleration of work cause by COVID-19		47
Number of site surveys being performed to mining claims | site	15,000
Minimum
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Estimated environmental obligations on an undiscounted and unescalated		3,300
Maximum
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Estimated environmental obligations on an undiscounted and unescalated		4,200
Pinal Creek, AZ; Newtown Creek, NY; Smelter Sites in Arizona, Indiana, Kansas, Missouri, New Jersey, Oklahoma, Pennsylvania; and Uranium Mining in Wester United States
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at end of year		$ 1,400