Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Significant Accounting Policies [Line Items]
Accrued interest receivable on available-for-sale securities	$ 4,900,000	$ 3,600,000
Allowances for doubtful accounts	600,000	600,000
Accruals for premium deficiency	0	0
Reinsurance Recoverable, Allowance for Credit Loss	0	0
Fair value, assets, level 1 to level 2 transfers	0	0
Fair value, assets, level 2 to level 1 transfers	0	0
Fair value, liabilities, level 1 to level 2 transfers	0	0
Fair value, liabilities, level 2 to level 1 transfers	$ 0	$ 0
Software
Schedule Of Significant Accounting Policies [Line Items]
Useful life of property and equipment	3 years
Minimum
Schedule Of Significant Accounting Policies [Line Items]
Useful life of property and equipment	3 years
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Useful life of property and equipment	27 years 6 months