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Basis of Presentation and Significant Accounting Policies Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended	12 Months Ended
	Apr. 29, 1991	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2016	Jun. 30, 2021	Dec. 31, 2019	Jul. 01, 2019	Apr. 30, 2013
Finite-Lived Intangible Assets [Line Items]
Operating Lease, Liability		$ 25	$ 25	$ 28
Income Taxes Paid			$ 6	$ 15	$ 11
Common Stock Voting Restrictions	10.00%
Common Stock, Par or Stated Value Per Share										$ 0.01
Entity Incorporation, Date of Incorporation	Apr. 29, 1991
Preferred stock, shares authorized		20,000,000	20,000,000	20,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01	$ 0.01							$ 0.01
Common stock, shares issued		46,658,990	46,658,990	46,477,068
Warrant Exercised During Period Shares			0	132	34
Common Stock Transfer Restrictions	5.00%
Common Stock Additional Transfer Restrictions						5.00%
Restricted Cash		$ 14	$ 14	$ 5	$ 13
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		61	61	23	35			$ 81
UK Income Tax Rate							19.00%		25.00%
Restricted Cash		$ 14	$ 14	$ 5	13
Weighted average period of future premiums			8 years	8 years
Estimated Future Premium Payments Weighted Average Discounted Rate		3.00%	3.00%	2.20%
CECL Securities Factor for Consideration		20.00%	20.00%
Xchange
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		14 years
Business Combination, Redeemable Noncontrolling Percentage		20.00%	20.00%
Business Combination, Redeemable Noncontrolling Percentage		20.00%	20.00%
Capacity Marine
Business Combination, Redeemable Noncontrolling Percentage		20.00%	20.00%
Business Combination, Redeemable Noncontrolling Percentage		20.00%	20.00%
All Trans
Business Combination, Redeemable Noncontrolling Percentage		15.00%	15.00%
Business Combination, Redeemable Noncontrolling Percentage		15.00%	15.00%
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
Fixed Income Securities [Member]
Investment income due and accrued		$ 10	$ 10	$ 10
Investment income due and accrued		10	10	10
Long-term Debt [Member]
Finite-Lived Intangible Assets [Line Items]
Interest Paid, Including Capitalized Interest, Operating and Investing Activities			283	80	107
Variable Interest Entity, Primary Beneficiary [Member]
Finite-Lived Intangible Assets [Line Items]
Restricted Cash		17	17	2	2
Restricted Cash		$ 17	$ 17	$ 2	$ 2
Estimated Future Premium Payments Weighted Average Discounted Rate		6.80%	6.80%	3.00%

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