Investments - Debt Securities Available-for-sale, Unrealized Loss Position, Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Line Items]
Gross unrealized losses		$ (8,700)
Debt securities due February 2028
Investments, Debt and Equity Securities [Line Items]
Basis	$ 4,814	4,717
Gross unrealized losses	(14)	(6)
Fair value	4,800	4,711
Debt securities due November 2051
Investments, Debt and Equity Securities [Line Items]
Basis	3,766	3,764
Gross unrealized losses	(106)	(215)
Fair value	3,660	3,549
Debt securities due March 2060
Investments, Debt and Equity Securities [Line Items]
Basis	5,583	5,805
Gross unrealized losses	(365)	(678)
Fair value	5,218	5,127
Debt securities due December 2060
Investments, Debt and Equity Securities [Line Items]
Basis	20,893	21,411
Gross unrealized losses	(5,074)	(4,242)
Fair value	15,819	17,169
Debt securities due January 2061
Investments, Debt and Equity Securities [Line Items]
Basis	4,886	4,886
Gross unrealized losses	(551)	(478)
Fair value	4,335	4,408
Debt securities due June 2061
Investments, Debt and Equity Securities [Line Items]
Basis	12,655	12,992
Gross unrealized losses	(1,071)	(1,243)
Fair value	11,584	11,749
Debt Securities due June 2061, Security One
Investments, Debt and Equity Securities [Line Items]
Gross unrealized losses	(500)	(300)
Debt Securities due June 2061, Security Two
Investments, Debt and Equity Securities [Line Items]
Gross unrealized losses	(500)	(900)
Debt securities due October 2061
Investments, Debt and Equity Securities [Line Items]
Basis	11,448	11,815
Gross unrealized losses	(1,048)	(842)
Fair value	10,400	10,973
Debt securities due March 2062
Investments, Debt and Equity Securities [Line Items]
Basis	9,842	10,315
Gross unrealized losses	(741)	(793)
Fair value	9,101	9,522
Debt Securities Due July 2062
Investments, Debt and Equity Securities [Line Items]
Basis	12,390	12,668
Gross unrealized losses	(776)	(41)
Fair value	11,614	12,627
Debt Securities Due October 2062
Investments, Debt and Equity Securities [Line Items]
Basis		17,174
Gross unrealized losses		(137)
Fair value		17,037
Total basis
Investments, Debt and Equity Securities [Line Items]
Basis	86,277	105,547
Total gross unrealized losses
Investments, Debt and Equity Securities [Line Items]
Gross unrealized losses	(9,746)	(8,675)
Total carrying value (fair value)
Investments, Debt and Equity Securities [Line Items]
Fair value	$ 76,531	$ 96,872