INVESTMENTS - Rollforward of Net Unrealized Investment Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning of year	$ 12,370	$ 18,492	$ 12,428	$ 19,492
Deferred income taxes	(341)	83	(541)	280
End of year	13,932	16,946	13,932	16,946
Accumulated Net Investment Gain (Loss) Attributable to Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning of year	323	(61)	(468)	679
Net investment gains (losses) arising during the period	1,623	(441)	3,206	(1,686)
Included in Net income (loss)	(4)	3	(7)	(85)
DAC	82	38	(573)	326
Deferred income taxes	(334)	76	(545)	273
Policyholders’ liabilities	(108)	14	(31)	122
End of year	1,584	(370)	1,584	(370)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, Net of Tax, Portion Attributable to Parent, Available-for-sale Securities	0	0	0	0
Debt Securities, Unrealized Gain (Loss), Excluding Other-than-temporary Impairment	1,582	(371)	1,582	(371)
Debt Securities, Unrealized Gain (Loss), With Other-than-temporary Impairment	2	1	2	1
Accumulated Net Investment Gain (Loss) Attributable to Parent | All other | Net Unrealized Gains (Losses) on Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning of year	1,003	193	(577)	1,526
Net investment gains (losses) arising during the period	1,623	(441)	3,206	(1,686)
Included in Net income (loss)	(4)	3	(7)	(85)
End of year	2,624	(244)	2,624	(244)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, Net of Tax, Portion Attributable to Parent, Available-for-sale Securities	0	0	0
Debt Securities, Unrealized Gain (Loss), Excluding Other-than-temporary Impairment	2,622	(245)	2,622	(245)
Debt Securities, Unrealized Gain (Loss), With Other-than-temporary Impairment	2	1	2	1
Accumulated Net Investment Gain (Loss) Attributable to Parent | All other | DAC
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning of year	(616)	(27)	39	(315)
DAC	82	38	(573)	326
End of year	(534)	11	(534)	11
Debt Securities, Unrealized Gain (Loss), Excluding Other-than-temporary Impairment	(534)	11	(534)	11
Accumulated Net Investment Gain (Loss) Attributable to Parent | All other | Policyholders’ Liabilities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning of year	22	(124)	(55)	(232)
Policyholders’ liabilities	(108)	14	(31)	122
End of year	(86)	(110)	(86)	(110)
Debt Securities, Unrealized Gain (Loss), Excluding Other-than-temporary Impairment	(86)	(110)	(86)	(110)
Accumulated Net Investment Gain (Loss) Attributable to Parent | All other | Deferred Income Tax Asset (Liability)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning of year	(86)	(103)	125	(300)
Deferred income taxes	(334)	76	(545)	273
End of year	(420)	(27)	(420)	(27)
Debt Securities, Unrealized Gain (Loss), Excluding Other-than-temporary Impairment	$ (420)	$ (27)	$ (420)	$ (27)