Employee Benefit Plans (Schedule of PRB Amounts Recognized in Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain) arising during the period	$ 971	$ (1,291)	$ (3,246)
Current year prior service cost	19	131	59
Amortization of prior service credit	568	(129)	$ (258)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain) arising during the period	36	(209)
Amortization of actuarial gain	31	11
Amortization of prior service credit	1	2
Net settlement and curtailment	2	3
Total recognized in other comprehensive income (loss)	70	(193)
Net recognized in net periodic expense (income) and other comprehensive loss	$ 69	$ (196)