Fair Value of Assets and Liabilities - Investments in Other investment company funds (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Fair value of investment in Other investments companies	$ 2,160,000	$ 1,930,000	$ 2,160,000
Unrealized gains or losses		(58,000)	(204,000)
Fair value of investments	3,650,000	3,750,000	3,650,000
Unrealized gains from change in fair value of investments		$ 103,000	$ 2,860,000
ASU 2022-03 | Change in accounting policy for investments
Other income	2,700,000
Other income net of tax	$ 2,200,000