REVISION OF PRIOR PERIOD FINANCIAL STATEMENTS - Cash Flow (Details) - USD ($) $ in Millions	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income (loss)			$ 5,425			$ (739)	$ 1,492	$ (311)		$ (617)	$ (1,467)	$ 2,189	$ 1,201
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Policy charges and fee income	$ (914)	$ (877)	(996)	$ (980)	$ (938)	(929)	(1,873)	(1,867)	$ (2,787)	(2,847)	(3,778)	(3,834)	(3,686)
Interest credited to policyholders’ account balances	306			320	317	307		624	930	944	1,263	1,067
Net derivative (gains) losses	1,472	6,038	(9,400)	453	237	1,633	(3,362)	1,870	(1,890)	2,323	4,012	250	(191)
Amortization and depreciation			1,330			227	1,540	420		564	675	296	386
Capitalization of deferred policy acquisition costs									(489)	(544)	(754)	(697)	(663)
Future policy benefits			1,925			64	1,807	41	1,867	943	962	(458)	1,111
Current and deferred income taxes			1,420			175	478	14	237	30	(102)	627	(9)
Other, net			(449)				(328)	(59)	46	(87)	(164)	(222)
Net cash provided by (used in) operating activities			(570)			(109)	(548)	(425)	5	(292)	(216)	61	(243)
Cash flows from financing activities:
Change in collateralized pledged assets			43				60		60	3
Change in collateralized pledged liabilities			646				239		(1,973)	(1,900)
Net cash provided by (used in) financing activities			(13)				2,891		8,176	7,713
Cash and cash equivalents, end of year	$ 8,684	8,364	10,315	4,471	4,734	5,129	8,364	4,734	$ 8,684	4,471	4,405	4,469	4,814
As Previously Reported
Cash flows from operating activities:
Net income (loss)			5,447			(709)	1,505	(279)		(595)	(1,436)	2,154	1,257
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Policy charges and fee income		(879)	(991)	(929)	(941)	(931)	(1,870)	(1,872)		(2,801)	(3,738)	(3,824)	(3,693)
Interest credited to policyholders’ account balances				304	314	304		618		922	1,241	1,090
Net derivative (gains) losses		6,033	(9,401)	451	236	1,630	(3,368)	1,866		2,317	4,000	231	(214)
Amortization and depreciation			1,275			239	1,506	433		535	657	257	399
Capitalization of deferred policy acquisition costs											(754)	(702)	(687)
Future policy benefits			1,936			22	1,828	1		925	947	(399)	1,097
Current and deferred income taxes			1,425			183	482	23		36	(108)	633	(10)
Other, net			(448)				(329)	(58)		(86)	(162)	(222)
Net cash provided by (used in) operating activities			(582)			(109)	(548)	(425)		(292)	(216)	61	(243)
Cash flows from financing activities:
Change in collateralized pledged assets			44				60
Change in collateralized pledged liabilities			657				239
Net cash provided by (used in) financing activities			(13)				2,891
Cash and cash equivalents, end of year		8,364	10,315	4,471	4,734	5,129	8,364	4,734		4,471	4,405	4,469	4,814
Impact of Revisions
Cash flows from operating activities:
Net income (loss)			(22)			(30)	(13)	(32)		(22)	(31)	35	(56)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Policy charges and fee income		2	(5)	(51)	3	2	(3)	5		(46)	(40)	(10)	7
Interest credited to policyholders’ account balances				16	3	3		6		22	22	(23)
Net derivative (gains) losses		5	1	2	1	3	6	4		6	12	19	23
Amortization and depreciation			55			(12)	34	(13)		29	18	39	(13)
Capitalization of deferred policy acquisition costs											0	5	24
Future policy benefits			(11)			42	(21)	40		18	15	(59)	14
Current and deferred income taxes			(5)			(8)	(4)	(9)		(6)	6	(6)	1
Other, net			(1)				1	(1)		(1)	(2)	0
Net cash provided by (used in) operating activities			12			0	0	0		0	0	0	0
Cash flows from financing activities:
Change in collateralized pledged assets			(1)				0
Change in collateralized pledged liabilities			(11)				0
Net cash provided by (used in) financing activities			(12)				0
Cash and cash equivalents, end of year		$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0		$ 0	$ 0	$ 0	$ 0