Reinsurance - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Ceded Credit Risk [Line Items]
Maximum amount beyond which net loss on any individual risk is limited through the purchase of reinsurance	$ 3,000,000.0
Percentage of reinsurance recoverables due from companies with financial strength ratings of "A" or better by A.M. Best and S&P rating services	88.00%
Amount of allowance for uncollectible amounts on paid recoverables	$ 15,900,000		$ 15,700,000
Reinsurance balances recoverable on unpaid losses and settlement expenses, allowances for uncollectible amounts	8,634,000		$ 9,402,000
Financing receivable, allowance for credit loss, write-off	0
Amount of allowance for uncollectible amounts due beyond one year	$ 0
Threshold period for including reinsurance receivables in the allowance for uncollectible amounts	1 year
Maximum
Ceded Credit Risk [Line Items]
Financing receivable, allowance for credit loss, recovery	$ 100,000
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
Ceded Credit Risk [Line Items]
Adoption impact of ASU 2016-13 on reinsurance balances recoverable		$ 1,300,000