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Investments (Narrative) (Details) $ in Millions	6 Months Ended
Investments (Narrative) (Details) $ in Millions	Jun. 30, 2025 USD ($) securities	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) securities
Investment Narrative [Line Items]
Securities As Percentage Of Consolidated Stockholder Equity	10.00%
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	100.00%		100.00%
Funds withheld at interest	$ 7,115		$ 5,436
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| securities	6,017,000		6,401
Financing Receivable, before Allowance for Credit Loss	$ 10,195		$ 8,952
Real Estate Held For Sale Transferred To Held For Use		$ 21
Financing Receivable, Modified in Period, Amount	35	47
Real Estate Acquired Through Foreclosure		$ 23
Real Estate Loans On A Nonaccrual Status	$ 29
CALIFORNIA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	12.70%
TEXAS
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	10.00%
CANADA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	6.80%
UNITED KINGDOM
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	2.20%
WASHINGTON
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	5.40%