Income Taxes - Valuation Allowance (Details) - USD ($) $ in Millions |
Dec. 31, 2023 |
Dec. 31, 2022 |
|---|---|---|
| Valuation Allowance [Line Items] | ||
| Total Valuation Allowance | $ 33 | $ 105 |
| U.S. federal and state net operating losses and other deferred tax assets | ||
| Valuation Allowance [Line Items] | ||
| Total Valuation Allowance | 8 | 16 |
| U.K. net operating losses and other deferred tax assets | ||
| Valuation Allowance [Line Items] | ||
| Total Valuation Allowance | $ 25 | $ 89 |