Employee Benefit Plans - Components of Net (Benefit) Cost (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2020 |
Sep. 30, 2019 |
Sep. 30, 2020 |
Sep. 30, 2019 |
|
| Pension Benefits | ||||
| Defined Benefit Plan Disclosure | ||||
| Service cost | $ 0 | $ 0 | $ 0 | $ 0 |
| Interest cost | 175 | 208 | 526 | 625 |
| Expected return on plan assets | (343) | (297) | (1,030) | (890) |
| Amortization of prior service credit | 0 | 0 | 0 | 0 |
| Recognized net actuarial loss | 74 | 73 | 223 | 219 |
| Special termination benefits | 0 | 0 | 0 | 0 |
| Settlements | 30 | 2 | 33 | 3 |
| Net periodic (benefit) cost | (64) | (14) | (248) | (43) |
| Other Postretirement and Postemployment Benefits | ||||
| Defined Benefit Plan Disclosure | ||||
| Service cost | 24 | 21 | 72 | 63 |
| Interest cost | 30 | 34 | 86 | 102 |
| Expected return on plan assets | (11) | (12) | (33) | (36) |
| Amortization of prior service credit | (2) | (2) | (7) | (7) |
| Recognized net actuarial loss | 10 | 9 | 32 | 29 |
| Special termination benefits | 1,260 | 0 | 1,260 | 0 |
| Settlements | 0 | 0 | 0 | 0 |
| Net periodic (benefit) cost | $ 1,311 | $ 50 | $ 1,410 | $ 151 |