Investments - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Gross unrealized gain (loss) on available for sale securities			$ 17,800,000
Proceeds from available-for-sale debt securities				$ 86,100,000	$ 29,300,000
Gross realized gains from sales of available-for-sale debt securities					5,000
Gross realized losses from sales of available-for-sale debt securities					155,000
Gross realized gains or losses from sale of available-for-sale debt securities	$ 0	$ 0		0	(149,000)
Amount payable for securities purchased	0	0		0	0
Amount receivable for securities sold	0	$ 0		0	$ 0
Gross unrealized gains				507,000		$ 0
Gross unrealized losses				549,000		638,000
Other than temporary impairments losses, investments				0		0
Investments	1,400,000			1,400,000		1,800,000
Deposits held in trust accounts	7,800,000			7,800,000		8,000,000
Deposits, held in trust for collateral requirements	$ 116,200,000			$ 116,200,000		$ 95,700,000