Employee Benefit Plans - Net Periodic Benefits Cost and Other Recognized in the OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Cost (Benefit)
Service cost	$ (3)	$ (4)	$ (4)
Interest cost	180	111	96
Expected return on plan assets	(235)	(202)	(205)
Amortization of prior service credit	0	0	0
Amortization of actuarial loss	29	62	69
Net periodic cost (benefit)	(23)	(25)	(36)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss)
Amortization of actuarial loss	29	62	69
Amortization of prior service credit	0	0	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	(142)	89	214
Prior service cost	0	0	0
Total	(113)	151	283
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net loss	(1,777)	(1,664)	(1,815)
Prior service credit	0	0	0
Total	(1,777)	(1,664)	(1,815)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Net Periodic Cost (Benefit)
Service cost	0	0	0
Interest cost	7	4	3
Expected return on plan assets	(1)	(2)	(3)
Amortization of prior service credit	(7)	(7)	(7)
Amortization of actuarial loss	5	7	8
Net periodic cost (benefit)	4	2	1
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss)
Amortization of actuarial loss	5	7	8
Amortization of prior service credit	(7)	(7)	(7)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	(6)	30	5
Prior service cost	0	0	0
Total	(8)	30	6
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net loss	(88)	(87)	(124)
Prior service credit	40	47	54
Total	$ (48)	$ (40)	$ (70)