Business Segments - Segment Premium Income by Distribution Channel and Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) numberOfSegments	Sep. 30, 2019 USD ($)
Segment Reporting [Abstract]
Number of segments | numberOfSegments			4
Segment Reporting Information [Line Items]
Amount	$ 961,817	$ 899,993	$ 2,845,354	$ 2,688,450
% of Total	100.00%	100.00%	100.00%	100.00%
Life
Segment Reporting Information [Line Items]
Amount	$ 674,021	$ 630,824	$ 1,994,473	$ 1,886,314
% of Total	100.00%	100.00%	100.00%	100.00%
Health
Segment Reporting Information [Line Items]
Amount	$ 287,795	$ 269,166	$ 850,877	$ 802,132
% of Total	100.00%	100.00%	100.00%	100.00%
Annuity
Segment Reporting Information [Line Items]
Amount	$ 1	$ 3	$ 4	$ 4
% of Total	100.00%	100.00%	100.00%	100.00%
American Income
Segment Reporting Information [Line Items]
Amount	$ 345,946	$ 318,461	$ 1,008,754	$ 937,111
% of Total	36.00%	35.00%	36.00%	35.00%
American Income | Life
Segment Reporting Information [Line Items]
Amount	$ 318,917	$ 293,149	$ 930,444	$ 863,250
% of Total	47.00%	47.00%	47.00%	46.00%
American Income | Health
Segment Reporting Information [Line Items]
Amount	$ 27,029	$ 25,312	$ 78,310	$ 73,861
% of Total	9.00%	9.00%	9.00%	9.00%
American Income | Annuity
Segment Reporting Information [Line Items]
Amount	$ 0	$ 0	$ 0	$ 0
% of Total	0.00%	0.00%	0.00%	0.00%
Direct to Consumer
Segment Reporting Information [Line Items]
Amount	$ 246,751	$ 230,828	$ 740,851	$ 705,174
% of Total	26.00%	26.00%	26.00%	26.00%
Direct to Consumer | Life
Segment Reporting Information [Line Items]
Amount	$ 227,734	$ 211,693	$ 682,978	$ 646,530
% of Total	34.00%	34.00%	34.00%	34.00%
Direct to Consumer | Health
Segment Reporting Information [Line Items]
Amount	$ 19,017	$ 19,135	$ 57,873	$ 58,644
% of Total	7.00%	7.00%	7.00%	7.00%
Direct to Consumer | Annuity
Segment Reporting Information [Line Items]
Amount	$ 0	$ 0	$ 0	$ 0
% of Total	0.00%	0.00%	0.00%	0.00%
Liberty National
Segment Reporting Information [Line Items]
Amount	$ 121,014	$ 119,251	$ 362,239	$ 356,894
% of Total	13.00%	13.00%	13.00%	13.00%
Liberty National | Life
Segment Reporting Information [Line Items]
Amount	$ 73,815	$ 71,812	$ 220,009	$ 214,007
% of Total	11.00%	11.00%	11.00%	11.00%
Liberty National | Health
Segment Reporting Information [Line Items]
Amount	$ 47,199	$ 47,439	$ 142,230	$ 142,887
% of Total	16.00%	18.00%	17.00%	18.00%
Liberty National | Annuity
Segment Reporting Information [Line Items]
Amount	$ 0	$ 0	$ 0	$ 0
% of Total	0.00%	0.00%	0.00%	0.00%
United American
Segment Reporting Information [Line Items]
Amount	$ 116,728	$ 105,717	$ 344,646	$ 316,275
% of Total	12.00%	12.00%	12.00%	12.00%
United American | Life
Segment Reporting Information [Line Items]
Amount	$ 2,402	$ 2,602	$ 7,373	$ 8,000
% of Total	0.00%	0.00%	0.00%	1.00%
United American | Health
Segment Reporting Information [Line Items]
Amount	$ 114,325	$ 103,112	$ 337,269	$ 308,271
% of Total	40.00%	38.00%	39.00%	39.00%
United American | Annuity
Segment Reporting Information [Line Items]
Amount	$ 1	$ 3	$ 4	$ 4
% of Total	100.00%	100.00%	100.00%	100.00%
Family Heritage
Segment Reporting Information [Line Items]
Amount	$ 81,306	$ 75,139	$ 238,339	$ 221,298
% of Total	8.00%	8.00%	8.00%	8.00%
Family Heritage | Life
Segment Reporting Information [Line Items]
Amount	$ 1,081	$ 971	$ 3,144	$ 2,829
% of Total	0.00%	0.00%	0.00%	0.00%
Family Heritage | Health
Segment Reporting Information [Line Items]
Amount	$ 80,225	$ 74,168	$ 235,195	$ 218,469
% of Total	28.00%	28.00%	28.00%	27.00%
Family Heritage | Annuity
Segment Reporting Information [Line Items]
Amount	$ 0	$ 0	$ 0	$ 0
% of Total	0.00%	0.00%	0.00%	0.00%
Other
Segment Reporting Information [Line Items]
Amount	$ 50,072	$ 50,597	$ 150,525	$ 151,698
% of Total	5.00%	6.00%	5.00%	6.00%
Other | Life
Segment Reporting Information [Line Items]
Amount	$ 50,072	$ 50,597	$ 150,525	$ 151,698
% of Total	8.00%	8.00%	8.00%	8.00%
Other | Health
Segment Reporting Information [Line Items]
Amount	$ 0	$ 0	$ 0	$ 0
% of Total	0.00%	0.00%	0.00%	0.00%
Other | Annuity
Segment Reporting Information [Line Items]
Amount	$ 0	$ 0	$ 0	$ 0
% of Total	0.00%	0.00%	0.00%	0.00%