REINSURANCE - Life Insurance In-Force and Effect of Reinsurance on Premiums Written and Earned (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net life insurance in-force
Direct life insurance in-force	$ 766,196,760	$ 765,986,223	$ 751,512,468
Amounts assumed from other companies	212,573,612	135,407,408	110,205,190
Amounts ceded to other companies	(271,600,818)	(302,149,614)	(328,377,398)
Net Amount	$ 707,169,554	$ 599,244,017	$ 533,340,260
Percentage of amount assumed to net	30.10%	22.60%	21.00%
Effect of reinsurance on premiums written and earned
Gross Amount	$ 3,175,881	$ 3,012,542	$ 2,996,646
Ceded to Other Companies	(1,517,204)	(1,383,510)	(1,367,096)
Assumed from Other Companies	880,321	643,966	459,716
Net Amount	2,538,998	2,272,998	2,089,266
Reinsurance receivables	4,400,000	4,500,000
Ceded benefits which are recoverable from reinsurers	86,300	116,100
Receivables related to insurance assumed	64,600	64,800
Life insurance
Effect of reinsurance on premiums written and earned
Gross Amount	2,852,899	2,681,191	2,655,846
Ceded to Other Companies	(1,383,822)	(1,249,906)	(1,230,258)
Assumed from Other Companies	835,677	626,283	435,113
Net Amount	2,304,754	2,057,568	1,860,701
Annuity policy fees	164,300	177,100	173,500
Accident/health insurance
Effect of reinsurance on premiums written and earned
Gross Amount	42,248	47,028	51,991
Ceded to Other Companies	(26,952)	(30,126)	(33,052)
Assumed from Other Companies	41,406	12,826	14,946
Net Amount	56,702	29,728	33,885
Property and liability insurance
Effect of reinsurance on premiums written and earned
Gross Amount	280,734	284,323	288,809
Ceded to Other Companies	(106,430)	(103,478)	(103,786)
Assumed from Other Companies	3,238	4,857	9,657
Net Amount	$ 177,542	$ 185,702	$ 194,680