SCHEDULE III - SUPPLEMENTARY INSURANCE INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	$ 3,519,555				$ 3,026,330				$ 3,519,555	$ 3,026,330	$ 2,205,401
Future  Policy Benefits and Claims	53,943,962				41,900,618				53,943,962	41,900,618	30,956,792
Unearned Premiums	794,832				769,620				794,832	769,620	751,130
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	21,310,515				20,083,191				21,310,515	20,083,191	16,886,759
Net Premiums and Policy Fees	622,345	$ 706,918	$ 602,020	$ 607,715	587,163	$ 603,982	$ 544,064	$ 537,789	2,538,998	2,272,998	2,089,266
Net Investment Income									2,818,830	2,338,902	1,923,056
Benefits and Settlement Expenses									4,256,062	3,511,252	2,955,007
Amortization of Deferred Policy Acquisitions Costs and Value of Businesses Acquired									175,653	226,066	79,443
Other Operating Expenses									836,906	774,110	814,211
Premiums Written									234,245	215,431	228,565
Life Marketing
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	1,486,699				1,499,386				1,486,699	1,499,386	1,320,776
Future  Policy Benefits and Claims	16,527,876				15,318,019				16,527,876	15,318,019	15,438,739
Unearned Premiums	91				98				91	98	107
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	397,758				422,037				397,758	422,037	424,204
Net Premiums and Policy Fees									1,105,531	1,043,228	1,011,911
Net Investment Income									571,654	552,697	550,714
Benefits and Settlement Expenses									1,498,024	1,412,001	1,319,138
Amortization of Deferred Policy Acquisitions Costs and Value of Businesses Acquired									157,854	116,917	120,753
Other Operating Expenses									55,888	69,758	60,877
Premiums Written									92	93	111
Acquisitions
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	924,090				458,976				924,090	458,976	74,862
Future  Policy Benefits and Claims	36,175,786				25,427,730				36,175,786	25,427,730	14,323,713
Unearned Premiums	1,991				2,206				1,991	2,206	2,423
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	6,386,506				6,018,954				6,386,506	6,018,954	4,377,020
Net Premiums and Policy Fees									1,172,557	952,315	785,188
Net Investment Income									1,532,605	1,108,218	752,520
Benefits and Settlement Expenses									2,236,701	1,636,697	1,204,084
Amortization of Deferred Policy Acquisitions Costs and Value of Businesses Acquired									10,693	18,690	(6,939)
Other Operating Expenses									232,169	143,698	110,607
Premiums Written									42,290	13,864	15,964
Annuities
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	929,917				889,697				929,917	889,697	772,633
Future  Policy Benefits and Claims	1,145,693				1,050,161				1,145,693	1,050,161	1,080,629
Unearned Premiums	0				0				0	0	0
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	9,004,199				8,324,931				9,004,199	8,324,931	7,308,354
Net Premiums and Policy Fees									65,744	71,321	73,617
Net Investment Income									367,650	335,382	316,582
Benefits and Settlement Expenses									267,368	223,912	216,324
Amortization of Deferred Policy Acquisitions Costs and Value of Businesses Acquired									(58,907)	24,274	(54,471)
Other Operating Expenses									152,700	148,615	146,407
Premiums Written									0	0	0
Stable Value Products
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	5,221				6,121				5,221	6,121	6,864
Future  Policy Benefits and Claims	0				0				0	0	0
Unearned Premiums	0				0				0	0	0
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	5,443,752				5,234,731				5,443,752	5,234,731	4,698,371
Net Premiums and Policy Fees									0	0	0
Net Investment Income									243,775	217,778	186,576
Benefits and Settlement Expenses									144,448	109,747	74,578
Amortization of Deferred Policy Acquisitions Costs and Value of Businesses Acquired									3,382	3,201	2,354
Other Operating Expenses									2,774	2,798	4,407
Premiums Written									0	0	0
Asset Protection
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	173,628				172,150				173,628	172,150	30,266
Future  Policy Benefits and Claims	43,604				51,702				43,604	51,702	55,030
Unearned Premiums	792,104				766,641				792,104	766,641	747,945
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	0				0				0	0	0
Net Premiums and Policy Fees									183,445	193,936	205,814
Net Investment Income									28,291	25,070	22,298
Benefits and Settlement Expenses									92,655	111,249	124,487
Amortization of Deferred Policy Acquisitions Costs and Value of Businesses Acquired									62,631	62,984	17,746
Other Operating Expenses									161,405	156,897	210,579
Premiums Written									180,095	189,283	199,741
Corporate and Other
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	0				0				0	0	0
Future  Policy Benefits and Claims	51,003				53,006				51,003	53,006	58,681
Unearned Premiums	646				675				646	675	655
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	$ 78,300				$ 82,538				78,300	82,538	78,810
Net Premiums and Policy Fees									11,721	12,198	12,736
Net Investment Income									74,855	99,757	94,366
Benefits and Settlement Expenses									16,866	17,646	16,396
Amortization of Deferred Policy Acquisitions Costs and Value of Businesses Acquired									0	0	0
Other Operating Expenses									231,970	252,344	281,334
Premiums Written									$ 11,768	$ 12,191	$ 12,749