Investments - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Investments Debt And Equity Securities [Abstract]
Proceeds from available-for-sale debt securities	$ 6,700,000	$ 14,200,000
Gross realized gains from sales of available-for-sale debt securities	0	27,000
Gross realized losses from sales of available-for-sale debt securities	0	6,000
Amount payable for securities purchased	750,000	0
Amount receivable for securities sold	1,300,000	$ 3,000
Other than temporary impairments losses, investments	0
Investments	1,200,000		$ 1,200,000
Deposits held in trust accounts	8,200,000		8,500,000
Deposits, held in trust for collateral requirements	$ 78,000,000.0		$ 76,100,000