Investment Securities - Allowance for Credit Loss Rollforward (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Debt Securities, Available-for-sale [Line Items]
Securities, available-for-sale, allowance for credit loss, beginning balance	$ (1,140)
Securities, available-for-sale, allowance for credit loss, ending balance	(1,537)
Corporate Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Securities, available-for-sale, allowance for credit loss, beginning balance	(1,140)	$ (929)
Additions for securities for which no previous expected credit losses were recognized	(2)	(153)
Change in securities for which a previous expected credit loss was recognized	(395)	(217)
Securities, available-for-sale, allowance for credit loss, ending balance	$ (1,537)	$ (1,299)