Deferred Policy Acquisition Costs - Changes in Insurance Subsidiaries' Deferred Policy Acquisition Costs (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Insurance [Abstract]
Balance, January 1	$ 60,615,127	$ 60,289,860	$ 56,309,196
Acquisition costs deferred	121,112,732	121,289,267	119,045,664
Amortization charged to earnings	(122,443,000)	(120,964,000)	(115,065,000)
Balance, December 31	$ 59,284,859	$ 60,615,127	$ 60,289,860