PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		$ (32)	$ 20	$ 17
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost		26	35	34
Defined Benefit Plan, Interest Cost		80	112	145
Defined Benefit Plan, Expected Return (Loss) on Plan Assets		(219)	(200)	(210)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		(1)	(1)	(1)
Defined Benefit Plan, Amortization of Gain (Loss)		116	110	84
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	$ (7)	(7)	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		(5)	56	52
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		(144)	240	202
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax		1	1	1
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax		(116)	(110)	(84)
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax		7	0	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax		(252)	131	119
Total recognized in net periodic benefit cost and other comprehensive loss or income		(257)	187	171
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost		1	1	1
Defined Benefit Plan, Interest Cost		3	5	7
Defined Benefit Plan, Expected Return (Loss) on Plan Assets		0	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		0	0	0
Defined Benefit Plan, Amortization of Gain (Loss)		(4)	(6)	(8)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment		0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		0	0	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		(36)	2	11
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax		0	0	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax		4	6	8
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax		0	0	0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax		(32)	8	19
Total recognized in net periodic benefit cost and other comprehensive loss or income		$ (32)	$ 8	$ 19