Business Segments - Segment Premium Income by Distribution Channel and Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) numberOfSegments	Mar. 31, 2019 USD ($)
Segment Reporting [Abstract]
Number of segments | numberOfSegments	4
Segment Reporting Information [Line Items]
Amount	$ 929,835	$ 890,973
% of Total	100.00%	100.00%
Life
Segment Reporting Information [Line Items]
Amount	$ 649,630	$ 624,289
% of Total	100.00%	100.00%
Health
Segment Reporting Information [Line Items]
Amount	$ 280,205	$ 266,684
% of Total	100.00%	100.00%
American Income
Segment Reporting Information [Line Items]
Amount	$ 328,579	$ 305,866
% of Total	35.00%	34.00%
American Income | Life
Segment Reporting Information [Line Items]
Amount	$ 302,852	$ 281,767
% of Total	47.00%	45.00%
American Income | Health
Segment Reporting Information [Line Items]
Amount	$ 25,727	$ 24,099
% of Total	9.00%	9.00%
Direct to Consumer
Segment Reporting Information [Line Items]
Amount	$ 239,839	$ 237,819
% of Total	26.00%	27.00%
Direct to Consumer | Life
Segment Reporting Information [Line Items]
Amount	$ 220,043	$ 217,559
% of Total	34.00%	35.00%
Direct to Consumer | Health
Segment Reporting Information [Line Items]
Amount	$ 19,796	$ 20,260
% of Total	7.00%	8.00%
Liberty National
Segment Reporting Information [Line Items]
Amount	$ 120,508	$ 118,873
% of Total	13.00%	13.00%
Liberty National | Life
Segment Reporting Information [Line Items]
Amount	$ 72,868	$ 70,717
% of Total	11.00%	11.00%
Liberty National | Health
Segment Reporting Information [Line Items]
Amount	$ 47,640	$ 48,156
% of Total	17.00%	18.00%
United American
Segment Reporting Information [Line Items]
Amount	$ 112,549	$ 105,656
% of Total	12.00%	12.00%
United American | Life
Segment Reporting Information [Line Items]
Amount	$ 2,490	$ 2,751
% of Total	0.00%	1.00%
United American | Health
Segment Reporting Information [Line Items]
Amount	$ 110,059	$ 102,905
% of Total	39.00%	38.00%
Family Heritage
Segment Reporting Information [Line Items]
Amount	$ 78,004	$ 72,195
% of Total	8.00%	8.00%
Family Heritage | Life
Segment Reporting Information [Line Items]
Amount	$ 1,021	$ 931
Family Heritage | Health
Segment Reporting Information [Line Items]
Amount	$ 76,983	$ 71,264
% of Total	28.00%	27.00%
Other
Segment Reporting Information [Line Items]
Amount	$ 50,356	$ 50,564
% of Total	6.00%	6.00%
Other | Life
Segment Reporting Information [Line Items]
Amount	$ 50,356	$ 50,564
% of Total	8.00%	8.00%