Investments (Narrative) (Details) - USD ($)	3 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Schedule of Investments [Line Items]
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	$ 15,500,000		$ 21,400,000
Certificates of deposit, at carrying value	0		700,000
Non-governmental issues exceeding 10% shareholders equity threshold	0		0
Allowance for credit loss	0		0
Credit-related investment impairment losses	0	$ 0
Asset Pledged as Collateral
Schedule of Investments [Line Items]
Carrying value of securities pledged	717,000,000		$ 886,000,000
Marketable equity securities
Schedule of Investments [Line Items]
Investment securities	$ 7,600,000