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Investments (Narrative) (Details) $ in Millions	9 Months Ended
Investments (Narrative) (Details) $ in Millions	Sep. 30, 2026 USD ($) securities	Sep. 30, 2025 USD ($)	Dec. 31, 2025 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	$ 7,870		$ 8,149
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions \| securities	9,044,000		5,968
Financing Receivable, before Allowance for Credit Loss	$ 12,344		$ 11,268
Financing Receivable, Modified in Period, Amount	71	$ 61
Mortgage Loans in Process of Foreclosure, Amount	21
Financing Receivable, Nonaccrual	$ 12
CALIFORNIA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	12.20%
TEXAS
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	8.80%
CANADA
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	5.90%
UNITED KINGDOM
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	1.50%
WASHINGTON
Investment Narrative [Line Items]
Mortgage Loans On Real Estate Commercial And Consumer Net Percentage Of Total	6.70%