Employee Benefit Plans (Amounts Recognized in the Balance Sheet) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Current pension and PRB liabilities (included in Accrued employee compensation)	$ 257	$ 256
Future pension and postretirement benefit obligations	2,060	2,104
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Non-current pension assets (included in Other assets)	2,130	1,819
Future pension and postretirement benefit obligations	1,493	1,532
PRB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Future pension and postretirement benefit obligations	502	523
Other pension and PRB related items
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Future pension and postretirement benefit obligations	$ 65	$ 49