Investments (Narrative) (Details)	3 Months Ended
	Mar. 31, 2023 USD ($) item security	Mar. 31, 2022 USD ($) security	Dec. 31, 2022 security
Schedule of Available-for-sale Securities [Line Items]
Number of investment in unaffiliated issuers | item	52
Investment in common stock (as percentage)	89.00%
Investment in debt securities (as percentage)	94.00%
Gross gains on investments	$ 1,500,000	$ 152,000
Gross losses on investments	2,100,000	6,000
Proceeds from sale of investment securities	50,400,000	$ 500,000
Debt securities, available-for-sale, allowance for expected credit losses	0
Realized gain (loss) on sale of securities	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of securities sold | security	0	0
Debt Securities [Member]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Number of Positions [Abstract]
Number of debt securities with unrealized loss | security	195		228
Number of debt securities with unrealized loss, less than 12 months | security	91		181
Number of debt securities with unrealized loss, greater than 12 months | security	104		47