Employee Benefits - Schedule of Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets (Details) - USD ($) $ in Millions |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Retirement Benefits [Abstract] | ||
| Projected benefit obligation | $ 2,161 | $ 1,892 |
| Fair value of plan assets | 1,748 | 1,499 |
| Accumulated benefit obligation | 2,018 | 1,768 |
| Fair value of plan assets | $ 1,748 | $ 1,499 |