Employee Benefit Plans (Components of Net Periodic Benefit Cost Included in General and Administrative Expenses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 328	$ 321	$ 291
Interest cost	364	429	489
Expected return on plan assets	(824)	(804)	(816)
Amortization of prior service cost	(3)	(4)	(4)
Amortization of actuarial (gain) loss, net	245	262	217
Settlements	5	9	59
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	(1)	0	0
Special termination benefits	1	7	26
Net periodic (benefit) cost	117	220	262
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	27	24	22
Interest cost	49	64	78
Expected return on plan assets	(102)	(100)	(95)
Amortization of prior service cost	6	6	4
Amortization of actuarial (gain) loss, net	16	16	24
Settlements	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0	0	0
Special termination benefits	0	0	1
Net periodic (benefit) cost	$ (4)	$ 10	$ 34