Employee Benefits - Schedule of Net Periodic Benefit (Income) Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected return on plan assets	$ (535)	$ (593)
Combined Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	56	59	$ 56
Interest cost	201	324	436
Settlement charges	383
Combined Pension Plan | Qualified Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	56	59	56
Interest cost	201	324	436
Expected return on plan assets	(535)	(593)	(618)
Settlement charges	383	0	0
Special termination benefits charge	6	13	6
Recognition of prior service credit	(9)	(9)	(8)
Recognition of actuarial loss	184	202	223
Net periodic pension expense (income)	286	(4)	95
Post-Retirement Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	14	14	15
Interest cost	47	69	110
Expected return on plan assets	0	(1)	(1)
Recognition of prior service credit	15	16	16
Recognition of actuarial loss	4	0	0
Curtailment loss	0	8	0
Net periodic pension expense (income)	$ 80	$ 106	$ 140