CONTINGENCIES (Environmental Obligations) (Details) site in Thousands, $ in Millions		12 Months Ended
	Jan. 17, 2017 USD ($) site divisions	Dec. 31, 2018 USD ($) state project	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Site Contingency [Line Items]
Number of remediation projects | project		100
Number of US States with remediation projects | state		26
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year		$ 1,439	$ 1,221	$ 1,215
Accretion Expense		100	84	81
Additionsb		56	241	26
Reductions		0	(43)	(43)
Spending		(84)	(64)	(58)
Balance at end of year		1,511	1,439	1,221
Less current portion		(132)	(134)	(129)
Long-term portion		1,379	1,305	$ 1,092
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
2019		132
2020		117
2021		119
2022		88
2023		100
Thereafter		2,700
Estimated environmental obligations on a discounted basis		1,400
Estimated environmental obligations on an undiscounted and unescalated		3,300
Environmental Loss Contingency, Number of Uranium Sites on Tribal Lands | divisions	94
Value of Consent Decree, Uranium Mines on Tribal Lands	$ 600
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
Number of site surveys being performed to mining claims | site	10
Minimum
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Estimated environmental obligations on an undiscounted and unescalated		2,700
Maximum
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Estimated environmental obligations on an undiscounted and unescalated		3,700
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		$ 1,300
Newtown Creek
Accrual for Environmental Loss Contingencies [Roll Forward]
Additionsb			138
Borough of Carteret
Accrual for Environmental Loss Contingencies [Roll Forward]
Additionsb			59
Uranium Mining Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Reductions			$ (41)