SIGNIFICANT TRANSACTIONS - Purchase Consideration (Details) - Life Business - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	May 01, 2018
ASSETS
Fixed maturities					$ 12,588,512
Mortgage loans					435,405
Policy loans					131,489
Total investments					13,155,406
Cash					20,669
Accrued investment income					151,610
Reinsurance receivables					337
Value of business acquired					336,437
Other assets					2,542
Total assets					13,667,001
LIABILITIES
Future policy benefits and claims					11,744,496
Unearned premiums					0
Total policy liabilities and accruals					11,744,496
Annuity account balances					1,823,444
Other policyholders’ funds					41,954
Other liabilities					57,107
Total liabilities					13,667,001
NET ASSETS ACQUIRED					0
Pro Forma [Abstract]
Revenue	$ 1,269,963	$ 1,418,743	$ 3,826,857	$ 4,170,636
Net income	$ 78,524	$ 152,971	$ 195,211	$ 369,826
Expected Amortization
Remainder of 2018					5,265
2019					21,063
2020					19,950
2021					18,329
2022					$ 16,611