Reinsurance - Total Ceded Reinsurance Transactions with both Affiliated and Unaffiliated Reinsurers (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Ceded Credit Risk [Line Items]
Premiums earned	$ 326,198,234	$ 310,179,267	$ 282,646,219
Prepaid reinsurance premiums	135,379,777	135,032,641
Affiliated Entity and Unaffiliated Entity [Member]
Ceded Credit Risk [Line Items]
Premiums earned	326,198,234	310,179,267	282,646,219
Losses and loss expenses	246,223,074	218,523,260	156,479,885
Prepaid reinsurance premiums	135,379,777	135,032,641	124,255,495
Liability for losses and loss expenses	$ 339,267,525	$ 293,271,257	$ 259,147,147