Pension and Other Postretirement Benefits (Components of Net Periodic Benefit Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Pension Benefits
Components of net periodic benefit cost:
Service cost	$ 63	$ 53	$ 170	$ 150
Interest cost	31	29	92	87
Expected return on plan assets	(36)	(38)	(110)	(122)
Amortization of prior service credit	(9)	(12)	(25)	(34)
Amortization of actuarial (gain) loss	3	(1)	5	(4)
Settlement gain	0	0	0	(2)
Net periodic benefit cost	52	31	132	75
Other Benefits
Components of net periodic benefit cost:
Service cost	5	4	15	14
Interest cost	8	7	24	23
Amortization of prior service credit	(5)	(5)	(16)	(16)
Net periodic benefit cost	$ 8	$ 6	$ 23	$ 21