Investments (Narrative) (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023
Schedule of Investments [Line Items]
Equity Securities, FV-NI	$ 6,200,000	$ 7,500,000
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	23,600,000	23,500,000
nongovernmentalissuerover10%ofequity	0	0
Debt Securities, Available-for-Sale, Allowance for Credit Loss	0	0
Asset Pledged as Collateral
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Restricted	$ 694,000,000	$ 709,000,000