Retirement Benefits Pension Plan Contributions (Details) - Pension Plan $ in Millions |
3 Months Ended |
|---|---|
|
Mar. 31, 2024
USD ($)
| |
| Defined Benefit Plan Disclosure [Line Items] | |
| Payment for Pension and Other Postretirement Benefits | $ 550 |
| Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year | 1,000 |
| Pension And Other Postretirement Expected Benefit Contributions Unfunded Plans | 420 |
| Pension and Other Postretirement Benefit Contributions Unfunded Plans | $ 105 |