Liability for Losses and Loss Expenses - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Increase (Decrease) in liability for losses and loss expenses of prior years	$ (12,932,277)	$ 35,631,610	$ 6,621,413
Percentage of 2010 development	2.70%	9.30%		1.90%
Personal Automobile [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Reserve created for commercial automobile	$ 20,800,000	$ 17,700,000