Employee Benefit Plans (Net Periodic Benefit Costs) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pension Benefits
Net periodic benefit costs [Abstract]
Service costs	$ 40	$ 38
Interest costs	114	118
Expected return on plan assets	(115)	(120)
Amortization of net actuarial (gains) losses	42	39
Amortization of prior service costs (credit)	(3)	(3)
Net periodic benefit costs (credit)	78	72
Other Postretirement Benefits
Net periodic benefit costs [Abstract]
Service costs	1	1
Interest costs	10	11
Expected return on plan assets	(14)	(13)
Amortization of net actuarial (gains) losses	(8)	(8)
Amortization of prior service costs (credit)	0	0
Net periodic benefit costs (credit)	$ (11)	$ (9)