Employee Benefit Plans (Components of Net Periodic Benefit Cost Included in General and Administrative Expenses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 51	$ 65	$ 154	$ 211
Interest cost	138	111	414	320
Expected return on plan assets	(231)	(218)	(694)	(649)
Amortization of prior service cost	(1)	(1)	(1)	(1)
Amortization of actuarial (gain) loss, net	17	37	51	124
Settlements	1	2	2	3
Curtailments	0	0	0	0
Special termination benefits	0	0	0	4
Net periodic (benefit) cost	(25)	(4)	(74)	12
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	3	7	10
Interest cost	17	14	53	41
Expected return on plan assets	(21)	(25)	(64)	(77)
Amortization of prior service cost	(2)	(2)	(6)	(6)
Amortization of actuarial (gain) loss, net	3	2	8	5
Settlements	0	0	0	0
Curtailments	0	0	0	(8)
Special termination benefits	0	0	0	4
Net periodic (benefit) cost	$ (1)	$ (8)	$ (2)	$ (31)