EMPLOYEE BENEFITS - Changes in the Fair Value of Pension Plan Assets, Projected Benefit Obligation, Funded Status, and Accumulated Benefit Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Qualified Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets as of January 1	$ 1,182	$ 1,390
Return on plan assets	169	(262)
Employer contributions	0	0
Benefits and administrative expenses paid	(70)	(76)
Fair value of plan assets from Investors acquisition	0	130
Fair value of plan assets as of December 31	1,281	1,182
Projected benefit obligation	880	868
Pension asset (obligation)	401	314
Accumulated benefit obligation	880	868
Non-Qualified Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets as of January 1	0	0
Return on plan assets	0	0
Employer contributions	5	8
Benefits and administrative expenses paid	(5)	(8)
Fair value of plan assets from Investors acquisition	0	0
Fair value of plan assets as of December 31	0	0
Projected benefit obligation	99	94
Pension asset (obligation)	(99)	(94)
Accumulated benefit obligation	$ 99	$ 94