Schedule IV. Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Life insurance in force, gross amount	$ 222,098,389	$ 217,350,660	$ 203,894,460
Life insurance in force, ceded to other companies	662,569	648,766	669,063
Life insurance in force, assumed from other companies	2,172,728	2,371,163	2,551,770
Life insurance in force, net amount	$ 223,608,548	$ 219,073,057	$ 205,777,167
Life insurance in force, percentage of amount assumed to net	1.00%	1.10%	1.20%
Premium, gross amount	$ 4,230,597	$ 4,061,326	$ 3,787,025
Premium, ceded to other companies	7,452	7,598	7,614
Premium, assumed from other companies	66,019	31,923	19,775
Premium, net amount	$ 4,289,164	$ 4,085,651	$ 3,799,186
Percentage of amount assumed to net	1.50%	0.80%	0.50%
Policy charges	$ 13,500	$ 14,200	$ 14,700
Life insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Premium, gross amount	2,995,104	2,868,759	2,642,555
Premium, ceded to other companies	4,361	4,286	4,241
Premium, assumed from other companies	19,009	19,502	19,775
Premium, net amount	$ 3,009,752	$ 2,883,975	$ 2,658,089
Percentage of amount assumed to net	0.60%	0.70%	0.70%
Health insurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Premium, gross amount	$ 1,235,493	$ 1,192,567	$ 1,144,470
Premium, ceded to other companies	3,091	3,312	3,373
Premium, assumed from other companies	47,010	12,421	0
Premium, net amount	$ 1,279,412	$ 1,201,676	$ 1,141,097
Percentage of amount assumed to net	3.70%	1.00%	0.00%