INVESTMENTS - DERIVATIVES OFFSETTING FINANCIAL ASSETS (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Equity contracts
Offsetting Assets [Line Items]
Gross Amounts Recognized	$ 4,132	$ 3,338
Gross Amounts Offset in the Balance Sheets	1,810	1,555
Net Amounts Presented in the Balance Sheets	2,322	1,783
Interest rate contracts
Offsetting Assets [Line Items]
Gross Amounts Recognized	330	320
Gross Amounts Offset in the Balance Sheets	653	191
Net Amounts Presented in the Balance Sheets	(323)	129
Credit contracts
Offsetting Assets [Line Items]
Gross Amounts Recognized	28	35
Gross Amounts Offset in the Balance Sheets	3	3
Net Amounts Presented in the Balance Sheets	25	32
Currency
Offsetting Assets [Line Items]
Gross Amounts Recognized	75	19
Gross Amounts Offset in the Balance Sheets	8	10
Net Amounts Presented in the Balance Sheets	67	9
Margin
Offsetting Assets [Line Items]
Gross Amounts Recognized	27	24
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts Presented in the Balance Sheets	27	24
Collateral
Offsetting Assets [Line Items]
Gross Amounts Recognized	65	4
Gross Amounts Offset in the Balance Sheets	2,134	1,855
Net Amounts Presented in the Balance Sheets	(2,069)	(1,851)
Total Derivatives, subject to an ISDA Master Agreement
Offsetting Assets [Line Items]
Gross Amounts Recognized	4,657	3,740
Gross Amounts Offset in the Balance Sheets	4,608	3,614
Net Amounts Presented in the Balance Sheets	49	126
Other financial instruments
Offsetting Assets [Line Items]
Gross Amounts Recognized	1,795	2,995
Gross Amounts Offset in the Balance Sheets	0	0
Net Amounts Presented in the Balance Sheets	1,795	2,995
Other invested assets
Offsetting Assets [Line Items]
Gross Amounts Recognized	6,452	6,735
Gross Amounts Offset in the Balance Sheets	4,608	3,614
Net Amounts Presented in the Balance Sheets	$ 1,844	$ 3,121