Employee Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Benefits
Net periodic benefit costs [Abstract]
Service costs	$ 38	$ 48	$ 113	$ 150
Interest costs	118	81	353	244
Expected return on plan assets	(119)	(128)	(360)	(386)
Amortization of net actuarial (gains) losses	40	31	118	92
Amortization of prior service costs (credit)	(3)	(4)	(9)	(10)
Net periodic benefit costs (credit)	74	28	215	90
Other Postretirement Benefits
Net periodic benefit costs [Abstract]
Service costs	1	2	2	4
Interest costs	11	8	32	25
Expected return on plan assets	(13)	(13)	(41)	(41)
Amortization of net actuarial (gains) losses	(7)	(7)	(22)	(19)
Amortization of prior service costs (credit)	0	0	0	0
Net periodic benefit costs (credit)	$ (8)	$ (10)	$ (29)	$ (31)