Investments - Debt Securities and Beneficial Interests (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Abstract]
Gross unrealized gains		$ 600,000
Gross unrealized losses		(8,700,000)
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
HTM, allowance for expected credit losses	$ 0	0
Basis	54,085,000	59,691,000
Gross unrealized gains	374,000	111,000
Gross unrealized losses	(998,000)	(629,000)
Fair value	53,461,000	59,173,000
Total Investments, Basis	275,453,000	303,449,000
Total Investments, Gross Unrealized Gains	6,666,000	4,379,000
Total Investments, Gross Unrealized Losses	(36,093,000)	(35,781,000)
Total Investments, Carrying Value	246,026,000	272,047,000
Interest receivable on securities, on available for sale debt securities	80,000	87,000
Interest receivable on held to maturity debt securities	19,000	24,000
Investment in beneficial interests
Debt Securities, Available-for-sale [Abstract]
Basis	88,577,000	104,162,000
Gross unrealized gains	5,148,000	3,631,000
Gross unrealized losses	(26,286,000)	(26,477,000)
Fair value	67,439,000	81,316,000
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Debt securities, available-for-sale, allowance for credit loss	9,082,000	6,880,000	$ 0	$ 0
Debt securities available-for-sale, at fair value
Debt Securities, Available-for-sale [Abstract]
Basis	132,791,000	139,596,000
Gross unrealized gains	1,144,000	637,000
Gross unrealized losses	(8,809,000)	(8,675,000)
Fair value	$ 125,126,000	$ 131,558,000