Business Segments - Segment Premium Income by Distribution Channel and Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) numberOfSegments	Jun. 30, 2019 USD ($)
Segment Reporting [Abstract]
Number of segments | numberOfSegments			4
Segment Reporting Information [Line Items]
Amount	$ 953,702	$ 897,484	$ 1,883,537	$ 1,788,457
% of Total	100.00%	100.00%	100.00%	100.00%
Life
Segment Reporting Information [Line Items]
Amount	$ 670,822	$ 631,201	$ 1,320,452	$ 1,255,490
% of Total	100.00%	100.00%	100.00%	100.00%
Health
Segment Reporting Information [Line Items]
Amount	$ 282,877	$ 266,282	$ 563,082	$ 532,966
% of Total	100.00%	100.00%	100.00%	100.00%
Annuity
Segment Reporting Information [Line Items]
Amount	$ 3	$ 1	$ 3	$ 1
% of Total	100.00%	100.00%	100.00%	100.00%
American Income
Segment Reporting Information [Line Items]
Amount	$ 334,229	$ 312,784	$ 662,808	$ 618,650
% of Total	35.00%	35.00%	35.00%	35.00%
American Income | Life
Segment Reporting Information [Line Items]
Amount	$ 308,675	$ 288,334	$ 611,527	$ 570,101
% of Total	46.00%	46.00%	46.00%	45.00%
American Income | Health
Segment Reporting Information [Line Items]
Amount	$ 25,554	$ 24,450	$ 51,281	$ 48,549
% 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	$ 254,261	$ 236,527	$ 494,100	$ 474,346
% of Total	27.00%	26.00%	26.00%	26.00%
Direct to Consumer | Life
Segment Reporting Information [Line Items]
Amount	$ 235,201	$ 217,278	$ 455,244	$ 434,837
% of Total	35.00%	35.00%	35.00%	35.00%
Direct to Consumer | Health
Segment Reporting Information [Line Items]
Amount	$ 19,060	$ 19,249	$ 38,856	$ 39,509
% 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	$ 120,717	$ 118,770	$ 241,225	$ 237,643
% of Total	13.00%	13.00%	13.00%	13.00%
Liberty National | Life
Segment Reporting Information [Line Items]
Amount	$ 73,326	$ 71,478	$ 146,194	$ 142,195
% of Total	11.00%	11.00%	11.00%	11.00%
Liberty National | Health
Segment Reporting Information [Line Items]
Amount	$ 47,391	$ 47,292	$ 95,031	$ 95,448
% of Total	17.00%	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	$ 115,369	$ 104,902	$ 227,918	$ 210,558
% of Total	12.00%	12.00%	12.00%	12.00%
United American | Life
Segment Reporting Information [Line Items]
Amount	$ 2,481	$ 2,647	$ 4,971	$ 5,398
% of Total	0.00%	0.00%	0.00%	1.00%
United American | Health
Segment Reporting Information [Line Items]
Amount	$ 112,885	$ 102,254	$ 222,944	$ 205,159
% of Total	40.00%	38.00%	40.00%	39.00%
United American | Annuity
Segment Reporting Information [Line Items]
Amount	$ 3	$ 1	$ 3	$ 1
% of Total	100.00%	100.00%	100.00%	100.00%
Family Heritage
Segment Reporting Information [Line Items]
Amount	$ 79,029	$ 73,964	$ 157,033	$ 146,159
% of Total	8.00%	8.00%	9.00%	8.00%
Family Heritage | Life
Segment Reporting Information [Line Items]
Amount	$ 1,042	$ 927	$ 2,063	$ 1,858
% of Total	0.00%	0.00%	0.00%	0.00%
Family Heritage | Health
Segment Reporting Information [Line Items]
Amount	$ 77,987	$ 73,037	$ 154,970	$ 144,301
% of Total	27.00%	28.00%	27.00%	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	$ 50,097	$ 50,537	$ 100,453	$ 101,101
% of Total	5.00%	6.00%	5.00%	6.00%
Other | Life
Segment Reporting Information [Line Items]
Amount	$ 50,097	$ 50,537	$ 100,453	$ 101,101
% 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%