Stock-Based Compensation - Analysis of Shares Available for Grant (Detail)	12 Months Ended
	Dec. 31, 2020 shares	Dec. 31, 2019 shares	Dec. 31, 2018 shares
Activity by Share-based Payment Award
Balance at January 1 (in shares)	7,167,718	9,422,760	2,964,320
Approval of Globe Life Inc. 2018 Incentive Plan (in shares)	0	0	8,984,000
Cancellation of available shares from prior plans (in shares)	0	0	(184,000)
Expired and forfeited during year (in shares)	38,820	20,800	41,317
Balance at December 31 (in shares)	5,984,418	7,167,718	9,422,760
Stock Options
Activity by Share-based Payment Award
Options granted during year (in shares)	(1,127,610)	(1,149,542)	(1,262,037)
Restricted Stock, Restricted Stock Units And Performance Shares
Activity by Share-based Payment Award
Restricted stock, restricted stock units, and performance shares granted (in shares)	(94,510)	(1,126,300)	(1,120,840)
Minimum
Activity by Share-based Payment Award
Ratio by which each grant of stock options reduces shares available for grant	0.85
Ratio by which each grant of restricted stock reduces shares available for options	3.10
Maximum
Activity by Share-based Payment Award
Ratio by which each grant of stock options reduces shares available for grant	1
Ratio by which each grant of restricted stock reduces shares available for options	3.88