RETIREMENT BENEFITS - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Change in accumulated other comprehensive income (loss)
Balance, beginning of period		$ 201,838
Change, net of tax	[1],[2]	(104)	$ 171
Balance, end of period		209,019	198,353	$ 201,838
Benefit plans
Change in accumulated other comprehensive income (loss)
Balance, beginning of period		(5,755)	(5,852)	(5,852)
Actuarial assumptions changes and plan experience		(269)	1,525	3,923
Net asset gain (loss) due to difference between actual and expected returns		183	(1,462)	(4,225)
Net amortization		43	64	198
Curtailment/settlement (gain)		(5)	0	(37)
Foreign exchange impact and other		(108)	50	172
Change in deferred taxes, net		52	(6)	66
Change, net of tax		(104)	171	97
Balance, end of period		$ (5,859)	$ (5,681)	$ (5,755)

[1] See Note 8.

[2] See Note 18.