CONTINGENCIES (Environmental Obligations) (Details) $ in Millions	1 Months Ended		12 Months Ended
	Sep. 30, 2025 USD ($)	Jul. 31, 2025 USD ($)	Dec. 31, 2025 USD ($) project state	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2017 USD ($) division site
Site Contingency [Line Items]
Number of remediation projects | project			80
Number of US States with remediation projects | state			23
Accrual for Environmental Loss Contingencies, Active Remediation Projects			$ 1,700
Active remediation projects, percent			85.00%
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year			$ 2,040	$ 1,939	$ 1,740
Accretion Expense			116	131	119
Net (reductions) additions			(19)	82	195
Spending			(119)	(112)	(115)
Balance at end of year			$ 2,018	$ 2,040	$ 1,939
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]			Liabilities	Liabilities	Liabilities
Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration]			Current portion of environmental and asset retirement obligations	Current portion of environmental and asset retirement obligations	Current portion of environmental and asset retirement obligations
Environmental Loss Contingency, Noncurrent, Statement of Financial Position [Extensible Enumeration]			Environmental and asset retirement obligations, less current portion	Environmental and asset retirement obligations, less current portion	Environmental and asset retirement obligations, less current portion
Less current portion			$ (125)	$ (131)	$ (131)
Long-term portion			1,893	1,909	1,808
Estimated environmental obligations on a discounted basis			(91)
Estimated environmental obligations on an undiscounted and unescalated			4,300
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
2026			125
2027			120
2028			118
2029			86
2030			61
Thereafter			3,800
Accrual for Environmental Loss Contingencies			2,018	$ 2,040	1,939
Environmental Loss Contingency, Number of Uranium Sites on Tribal Lands | division						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
Environmental Loss Contingency, Number of Uranium Sites on Tribal Lands Excluded | division						23
Number of site surveys being performed to mining claims | site						15,000
FMC
Accrual for Environmental Loss Contingencies [Roll Forward]
Estimated environmental obligations on a discounted basis			1,800
Minimum
Accrual for Environmental Loss Contingencies [Roll Forward]
Estimated environmental obligations on an undiscounted and unescalated			3,800
Maximum
Accrual for Environmental Loss Contingencies [Roll Forward]
Estimated environmental obligations on an undiscounted and unescalated			5,000
Pinal Creek, AZ
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at end of year			520
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Accrual for Environmental Loss Contingencies			520
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)			61
Newtown Creek
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at end of year			486
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Accrual for Environmental Loss Contingencies			486
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)					$ 64
Uranium Mining Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at end of year			482
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Accrual for Environmental Loss Contingencies			482
Historical Smelter Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at end of year			224
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Accrual for Environmental Loss Contingencies			$ 224
Cateret
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)	$ 19
Arthur Kill
Estimated environmental cash payments (on an undiscounted and unescalated basis) [Abstract]
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)		$ 46