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v3.20.4

Basis of Presentation and Significant Accounting Policies Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2020 | Dec. 31, 2020 | Jul. 01, 2019 | Jun. 30, 2019
Finite-Lived Intangible Assets [Line Items] |  |  |  |
Operating Lease, Liability | $ 30 | $ 30 |  |
Income Taxes Paid |  | $ 11 |  |
Common Stock, Par or Stated Value Per Share | $ 0.01 | $ 0.01 |  |
Preferred stock, shares authorized | 20,000,000 | 20,000,000 |  |
Preferred Stock, Par or Stated Value Per Share | $ 0.01 | $ 0.01 |  |
Common stock, shares issued | 45,865,081 | 45,865,081 |  |
Warrant Exercised During Period Shares |  | 34 |  |
Cash and cash equivalents | $ 20 | $ 20 |  |
Restricted Cash | 13 | 13 |  |
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents | 35 | 35 |  |
UK Income Tax Rate |  |  | 19.00% | 17.00%
Restricted Cash | $ 13 | $ 13 |  |
Weighted average period of future premiums |  | 8 years 3 months 18 days |  |
Estimated Future Premium Payments Weighted Average Discounted Rate | 2.20% | 2.20% |  |
Business Combination, Redeemable Noncontrolling Percentage | 20.00% | 20.00% |  |
Xchange |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |
Finite-Lived Intangible Asset, Useful Life | 14 years |  |  |
Restricted Cash | $ 4 | $ 4 |  |
Restricted Cash | $ 4 | $ 4 |  |
Minimum [Member] | Furniture and Fixtures [Member] |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  | 3 years |  |
Maximum [Member] | Furniture and Fixtures [Member] |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  | 5 years |  |
Long-term Debt [Member] |  |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |  |
Interest Paid, Including Capitalized Interest, Operating and Investing Activities |  | $ 107 |  |
Variable Interest Entity, Primary Beneficiary [Member] |  |  |  |
Estimated Future Premium Payments Weighted Average Discounted Rate | 2.40% | 2.40% |  |

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