SIGNIFICANT TRANSACTIONS - Purchase Consideration (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jun. 01, 2019	May 01, 2018
Life Business
Assets
Fixed maturities				$ 12,588,512
Mortgage loans				435,405
Policy loans				131,489
Total investments				13,155,406
Cash				38,457
Accrued investment income				152,030
Reinsurance receivables				272
Value of business acquired				374,739
Other assets				916
Total assets				13,721,820
Liabilities
Future policy benefits and claims				11,750,196
Unearned premiums				0
Total policy liabilities and accruals				11,750,196
Annuity account balances				1,864,141
Other policyholders’ funds				41,936
Other liabilities				65,547
Total liabilities				13,721,820
Net assets acquired				$ 0
Business Acquisition, Pro Forma Information [Abstract]
Revenue	$ 5,082,755	$ 5,548,132
Net Income	240,071	1,309,876
Individual Life Business
Assets
Fixed maturities			$ 8,697,966
Mortgage loans			1,386,228
Policy loans			44,002
Other long-term investments			1,521,965
Total investments			11,650,161
Cash			34,835
Accrued investment income			101,452
Accounts and premiums receivable			62
Reinsurance receivables			1,642
Value of business acquired			514,124
Other intangibles			21,300
Other assets			5,525
Assets related to separate accounts			9,583,217
Total assets			21,912,318
Liabilities
Future policy benefits and claims			11,000,822
Annuity account balances			220,064
Other policyholders’ funds			220,117
Other liabilities			75,456
Liabilities related to separate accounts			9,583,217
Total liabilities			21,099,676
Net assets acquired			$ 812,642
Business Acquisition, Pro Forma Information [Abstract]
Revenue	6,322,962	5,592,419
Net Income	$ 570,079	$ 253,238