Goodwill and Other Intangible Assets - Estimated Aggregate Pre-Tax Amortization Expense Related to Intangible Assets (Details) $ in Millions |
Mar. 31, 2018
USD ($)
|
|---|---|
| Goodwill and Intangible Assets Disclosure [Abstract] | |
| Amortization expense remainder of 2018 | $ 7 |
| Amortization expense 2019 | 8 |
| Amortization expense 2020 | 7 |
| Amortization expense 2021 | 7 |
| Amortization expense 2022 | $ 7 |