SCHEDULE III - SUPPLEMENTARY INSURANCE INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	$ 3,419,684				$ 3,519,555				$ 3,419,684	$ 3,519,555	$ 3,026,330
Future  Policy Benefits and Claims	54,107,894				53,943,962				54,107,894	53,943,962	41,900,618
Unearned Premiums	781,806				794,832				781,806	794,832	769,620
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	23,399,242				21,310,515				23,399,242	21,310,515	20,083,191
Net Premiums and Policy Fees	690,594	$ 741,416	$ 632,539	$ 842,847	606,455	$ 690,951	$ 586,182	$ 592,169	2,907,396	2,475,757	2,272,998
Net Investment Income									2,882,963	2,818,830	2,338,902
Benefits and Settlement Expenses									4,900,537	4,256,062	3,511,252
Amortization of DAC and VOBA									208,472	175,653	226,066
Other Operating Expenses									774,889	773,665	774,110
Premiums Written									206,667	234,245	215,431
Retail Life and Annuity
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	2,479,781				2,416,616				2,479,781	2,416,616	2,389,083
Future  Policy Benefits and Claims	18,483,084				17,673,569				18,483,084	17,673,569	16,368,180
Unearned Premiums	85				91				85	91	98
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	10,913,608				9,401,957				10,913,608	9,401,957	8,746,968
Net Premiums and Policy Fees									1,472,253	1,171,275	1,114,549
Net Investment Income									1,008,016	939,304	888,079
Benefits and Settlement Expenses									2,165,931	1,765,392	1,635,913
Amortization of DAC and VOBA									116,021	98,947	141,191
Other Operating Expenses									197,285	208,588	218,373
Premiums Written									86	92	93
Acquisitions
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	761,475				924,090				761,475	924,090	458,976
Future  Policy Benefits and Claims	35,536,821				36,175,786				35,536,821	36,175,786	25,427,730
Unearned Premiums	1,642				1,991				1,642	1,991	2,206
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	6,360,687				6,386,506				6,360,687	6,386,506	6,018,954
Net Premiums and Policy Fees									1,316,648	1,172,557	952,315
Net Investment Income									1,648,122	1,532,605	1,108,218
Benefits and Settlement Expenses									2,511,400	2,236,701	1,636,697
Amortization of DAC and VOBA									23,445	10,693	18,690
Other Operating Expenses									266,765	232,169	143,698
Premiums Written									90,413	42,290	13,864
Stable Value Products
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	8,336				5,221				8,336	5,221	6,121
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	6,056,181				5,443,752				6,056,181	5,443,752	5,234,731
Net Premiums and Policy Fees									0	0	0
Net Investment Income									230,217	243,775	217,778
Benefits and Settlement Expenses									133,034	144,448	109,747
Amortization of DAC and VOBA									3,322	3,382	3,201
Other Operating Expenses									4,251	2,774	2,798
Premiums Written									0	0	0
Asset Protection
Supplementary insurance information
Deferred Policy Acquisition Costs and Value of Businesses Acquired	170,092				173,628				170,092	173,628	172,150
Future  Policy Benefits and Claims	40,116				43,604				40,116	43,604	51,702
Unearned Premiums	779,397				792,104				779,397	792,104	766,641
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	0				0				0	0	0
Net Premiums and Policy Fees									107,454	120,204	193,936
Net Investment Income									23,379	28,291	25,070
Benefits and Settlement Expenses									75,468	92,655	111,249
Amortization of DAC and VOBA									65,684	62,631	62,984
Other Operating Expenses									92,408	98,164	156,897
Premiums Written									105,121	180,095	189,283
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	47,873				51,003				47,873	51,003	53,006
Unearned Premiums	682				646				682	646	675
Stable Value Products, Annuity Contracts  and Other Policyholders’ Funds	$ 68,766				$ 78,300				68,766	78,300	82,538
Net Premiums and Policy Fees									11,041	11,721	12,198
Net Investment Income									(26,771)	74,855	99,757
Benefits and Settlement Expenses									14,704	16,866	17,646
Amortization of DAC and VOBA									0	0	0
Other Operating Expenses									214,180	231,970	252,344
Premiums Written									$ 11,047	$ 11,768	$ 12,191