Employee Benefit Plans (Net Periodic Costs (Components of Net Periodic Benefit Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Plans | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 130	$ 142	$ 133
Interest cost	249	156	139
Expected return on plan assets	(324)	(298)	(273)
Amortization of prior service cost	4	3	4
Net periodic cost	59	3	3
Current year prior service (credit)			(4)
Amortization of prior service (cost)	(4)	(3)	(4)
Current year actuarial loss/(gain)	(173)	508	(485)
Total recognized in OCI	(177)	505	(493)
Total amounts recognized in net periodic cost and OCI	(118)	508	(490)
Pension Plans | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	3	4
Interest cost	11	7	6
Amortization of actuarial loss	1	5	6
Net periodic cost	15	15	16
Current year actuarial loss/(gain)	3	(44)	(4)
Amortization of actuarial (loss)	(1)	(5)	(6)
Total recognized in OCI	2	(49)	(10)
Total amounts recognized in net periodic cost and OCI	17	(34)	6
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	4	4
Interest cost	14	9	8
Expected return on plan assets	(10)	(6)	(6)
Net periodic cost	7	7	6
Current year actuarial loss/(gain)	1	(30)	(7)
Total recognized in OCI	1	(30)	(7)
Total amounts recognized in net periodic cost and OCI	$ 8	$ (23)	$ (1)