Unpaid Losses and Loss Adjustment Expenses - Narrative (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Liability For Claims And Claims Adjustment Expense [Line Items]
Losses and loss adjustment expenses, net	$ 16,159,000		$ 14,553,000	$ 53,447,000	$ 40,767,000
Prior year adjustments	3,646,000		4,695,000	15,634,000	11,481,000
Winter Storm Uri
Liability For Claims And Claims Adjustment Expense [Line Items]
Losses and loss adjustment expenses, net		$ 2,000,000.0
2017 Accident Year
Liability For Claims And Claims Adjustment Expense [Line Items]
Prior year adjustments	1,100,000			5,000,000.0
2018 Accident Year
Liability For Claims And Claims Adjustment Expense [Line Items]
Prior year adjustments	1,400,000			4,800,000
2019 Accident Year
Liability For Claims And Claims Adjustment Expense [Line Items]
Prior year adjustments	1,000,000.0			3,400,000
2020 Accident Year
Liability For Claims And Claims Adjustment Expense [Line Items]
Prior year adjustments				2,400,000
Commercial Lines1
Liability For Claims And Claims Adjustment Expense [Line Items]
Prior year adjustments	3,400,000		$ 4,700,000	14,700,000	$ 11,500,000
Personal Lines
Liability For Claims And Claims Adjustment Expense [Line Items]
Prior year adjustments	$ 290,000			$ 926,000