Investments in Fixed Maturity Securities (Narrative) (Details) $ in Millions	Dec. 31, 2024 USD ($)
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items]
Debt Securities, Held-to-maturity, Restricted	$ 1,223
Insurance
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items]
Debt Securities, Held-to-maturity, Restricted	884
Reinsurance & Monoline Excess
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items]
Debt Securities, Held-to-maturity, Restricted	33
Letters of Credit Outstanding, Amount	27
523991 Trust, Fiduciary, and Custody Activities
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items]
Debt Securities, Held-to-maturity, Restricted	$ 2,167