Employee Benefit Plans - Net Periodic Benefits Cost and Other Recognized in the OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Cost (Benefit)
Service cost	$ (4)	$ (4)	$ (4)
Interest cost	96	127	159
Expected return on plan assets	(205)	(215)	(226)
Amortization of prior service credit	0	0	0
Amortization of actuarial loss	69	60	44
Net periodic cost (benefit)	(36)	(24)	(19)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss)
Amortization of actuarial loss	69	60	44
Amortization of prior service credit	0	0	0
Prior service cost (credit)	214	(106)	(88)
Prior service cost	0	0	0
Total	283	(46)	(44)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net loss	(1,815)	(2,098)	(2,052)
Prior service credit	0	0	0
Total	(1,815)	(2,098)	(2,052)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Net Periodic Cost (Benefit)
Service cost	0	0	0
Interest cost	3	6	8
Expected return on plan assets	(3)	(4)	(4)
Amortization of prior service credit	(7)	(7)	(7)
Amortization of actuarial loss	8	7	6
Net periodic cost (benefit)	1	2	3
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss)
Amortization of actuarial loss	8	7	6
Amortization of prior service credit	(7)	(7)	(7)
Prior service cost (credit)	5	(11)	(18)
Prior service cost	0	0	2
Total	6	(11)	(17)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net loss	(124)	(136)	(132)
Prior service credit	54	60	67
Total	$ (70)	$ (76)	$ (65)