Intangible Assets - Narrative (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Finite-Lived Intangible Assets | |||
| Amortization expense | $ 11 | $ 17 | $ 17 |
| Estimated amortization expense in 2020 | 9 | ||
| Estimated amortization expense in 2021 | 9 | ||
| Estimated amortization expense in 2022 | 9 | ||
| Estimated amortization expense in 2023 | 9 | ||
| Estimated amortization expense in 2024 | $ 9 | ||