Business Segments - Segment Premium Revenue by Distribution Channel and Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) numberOfSegments	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting [Abstract]
Number of segments | numberOfSegments	4
Segment Reporting Information [Line Items]
Amount	$ 3,595,134	$ 3,421,906	$ 3,282,935
% of Total	100.00%	100.00%	100.00%
Life
Segment Reporting Information [Line Items]
Amount	$ 2,517,784	$ 2,406,555	$ 2,306,547
% of Total	100.00%	100.00%	100.00%
Health
Segment Reporting Information [Line Items]
Amount	$ 1,077,346	$ 1,015,339	$ 976,373
% of Total	100.00%	100.00%	100.00%
Annuity
Segment Reporting Information [Line Items]
Amount	$ 4	$ 12	$ 15
% of Total	100.00%	100.00%	100.00%
American Income
Segment Reporting Information [Line Items]
Amount	$ 1,259,942	$ 1,174,646	$ 1,088,315
% of Total	35.00%	34.00%	33.00%
American Income | Life
Segment Reporting Information [Line Items]
Amount	$ 1,160,495	$ 1,081,333	$ 999,279
% of Total	46.00%	45.00%	43.00%
American Income | Health
Segment Reporting Information [Line Items]
Amount	$ 99,447	$ 93,313	$ 89,036
% of Total	9.00%	9.00%	9.00%
Direct to Consumer
Segment Reporting Information [Line Items]
Amount	$ 933,100	$ 905,232	$ 886,375
% of Total	26.00%	26.00%	27.00%
Direct to Consumer | Life
Segment Reporting Information [Line Items]
Amount	$ 855,543	$ 828,935	$ 812,907
% of Total	34.00%	34.00%	35.00%
Direct to Consumer | Health
Segment Reporting Information [Line Items]
Amount	$ 77,557	$ 76,297	$ 73,468
% of Total	7.00%	7.00%	8.00%
Liberty National
Segment Reporting Information [Line Items]
Amount	$ 475,129	$ 470,256	$ 470,842
% of Total	13.00%	14.00%	14.00%
Liberty National | Life
Segment Reporting Information [Line Items]
Amount	$ 285,551	$ 278,878	$ 274,635
% of Total	11.00%	12.00%	12.00%
Liberty National | Health
Segment Reporting Information [Line Items]
Amount	$ 189,578	$ 191,378	$ 196,207
% of Total	18.00%	19.00%	20.00%
United American
Segment Reporting Information [Line Items]
Amount	$ 427,157	$ 392,539	$ 376,690
% of Total	12.00%	12.00%	12.00%
United American | Life
Segment Reporting Information [Line Items]
Amount	$ 10,571	$ 11,451	$ 12,547
% of Total	1.00%	1.00%	1.00%
United American | Health
Segment Reporting Information [Line Items]
Amount	$ 416,582	$ 381,076	$ 364,128
% of Total	39.00%	38.00%	37.00%
United American | Annuity
Segment Reporting Information [Line Items]
Amount	$ 4	$ 12	$ 15
% of Total	100.00%	100.00%	100.00%
Family Heritage
Segment Reporting Information [Line Items]
Amount	$ 298,012	$ 276,776	$ 256,727
% of Total	8.00%	8.00%	8.00%
Family Heritage | Life
Segment Reporting Information [Line Items]
Amount	$ 3,830	$ 3,501	$ 3,193
Family Heritage | Health
Segment Reporting Information [Line Items]
Amount	$ 294,182	$ 273,275	$ 253,534
% of Total	27.00%	27.00%	26.00%
Other
Segment Reporting Information [Line Items]
Amount	$ 201,794	$ 202,457	$ 203,986
% of Total	6.00%	6.00%	6.00%
Other | Life
Segment Reporting Information [Line Items]
Amount	$ 201,794	$ 202,457	$ 203,986
% of Total	8.00%	8.00%	9.00%