INVESTMENTS - DERIVATIVES OFFSETTING FINANCIAL ASSETS (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Equity contracts
Offsetting Assets [Line Items]
Gross Amounts Recognized	$ 3,404	$ 3,338
Gross Amounts Offset in the Balance Sheets	1,407	1,555
Net Amounts Presented in the Balance Sheets	1,997	1,783
Interest rate contracts
Offsetting Assets [Line Items]
Gross Amounts Recognized	302	320
Gross Amounts Offset in the Balance Sheets	347	191
Net Amounts Presented in the Balance Sheets	(45)	129
Credit contracts
Offsetting Assets [Line Items]
Gross Amounts Recognized	32	35
Gross Amounts Offset in the Balance Sheets	3	3
Net Amounts Presented in the Balance Sheets	29	32
Currency
Offsetting Assets [Line Items]
Gross Amounts Recognized	10	19
Gross Amounts Offset in the Balance Sheets	52	10
Net Amounts Presented in the Balance Sheets	(42)	9
Margin
Offsetting Assets [Line Items]
Gross Amounts Recognized	16	24
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts Presented in the Balance Sheets	16	24
Collateral
Offsetting Assets [Line Items]
Gross Amounts Recognized	8	4
Gross Amounts Offset in the Balance Sheets	1,824	1,855
Net Amounts Presented in the Balance Sheets	(1,816)	(1,851)
Total Derivatives, subject to an ISDA Master Agreement
Offsetting Assets [Line Items]
Gross Amounts Recognized	3,772	3,740
Gross Amounts Offset in the Balance Sheets	3,633	3,614
Net Amounts Presented in the Balance Sheets	139	126
Total Derivatives
Offsetting Assets [Line Items]
Gross Amounts Recognized	3,772	3,740
Gross Amounts Offset in the Balance Sheets	3,633	3,614
Net Amounts Presented in the Balance Sheets	139	126
Other financial instruments
Offsetting Assets [Line Items]
Gross Amounts Recognized	3,435	2,995
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts Presented in the Balance Sheets	3,435	2,995
Other invested assets
Offsetting Assets [Line Items]
Gross Amounts Recognized	7,207	6,735
Gross Amounts Offset in the Balance Sheets	3,633	3,614
Net Amounts Presented in the Balance Sheets	$ 3,574	$ 3,121