Reinsurance - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019 USD ($) contract	Dec. 31, 2018 USD ($)
Effects of Reinsurance [Line Items]
Loss per worker's compensation retained	$ 1,000,000.0
Loss per non-worker's compensation retained	1,500,000
Property and liability losses per risk	6,000,000
Excess casualty clash coverage	60,000,000
Facultative reinsurance cover purchased	20,000,000
Corporate catastrophe coverage	500,000,000
Catastrophe amount retained	$ 17,500,000
Number of coverage contracts | contract	2
Amount receivable from reinsurers	$ 411,830,000	$ 427,475,000
Litigation or dispute with reinsurers involved	0
Maximum
Effects of Reinsurance [Line Items]
Additional excess property per risk coverage	20,000,000
Zero to Seventy-Five Issue Ages
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	5,475,000
Zero to Seventy-Five Issue Ages | Individual Life
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	5,000,000.0
Zero to Seventy-Five Issue Ages | Individual Accidental Death
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	250,000
Zero to Seventy-Five Issue Ages | Group Life
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	100,000
Zero to Seventy-Five Issue Ages | Credit Life
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	125,000
Seventy-Six to Eighty Issue Ages
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	2,475,000
Seventy-Six to Eighty Issue Ages | Individual Life
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	2,000,000.0
Seventy-Six to Eighty Issue Ages | Individual Accidental Death
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	250,000
Seventy-Six to Eighty Issue Ages | Group Life
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	100,000
Seventy-Six to Eighty Issue Ages | Credit Life
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	125,000
Eighty-One and Over Issue Ages
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	1,475,000
Eighty-One and Over Issue Ages | Individual Life
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	1,000,000.0
Eighty-One and Over Issue Ages | Individual Accidental Death
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	250,000
Eighty-One and Over Issue Ages | Group Life
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	100,000
Eighty-One and Over Issue Ages | Credit Life
Effects of Reinsurance [Line Items]
Maximum amount retained by insurance company	125,000
First Contract
Effects of Reinsurance [Line Items]
Catastrophe aggregate reinsurance coverage	30,000,000
Aggregated catastrophe losses	90,000,000
Contribution against aggregation of loss	10,000,000
Second Contract
Effects of Reinsurance [Line Items]
Annual limit of catastrophe aggregate reinsurance coverage	35,000,000
Annual aggregate deductible	40,000,000
Catastrophe aggregate reinsurance coverage	35,000,000
Reinsurance claim base amount loss	$ 5,000,000
Catastrophe aggregate reinsurance coverage percentage	87.75%
Reinsurance retention policy description	This cover was placed at 87.75% on July 1, 2019.