REVISION OF PRIOR PERIOD FINANCIAL STATEMENTS - Equity (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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other	$ 0			$ 24		$ (7)			$ 20	$ 8
Beginning of year	19,038	$ 21,535	$ 15,047	16,217	$ 14,591	15,368	$ 15,047	$ 15,368	15,047	15,368	$ 15,368	$ 16,411
Net income (loss) attributable to Holdings	(779)	(4,019)	5,388	(374)	361	(805)	1,369	(444)	590	(818)	(1,764)	1,855	$ 778
Other comprehensive income (loss)	266	1,642	1,437	752	1,311	884	3,079	2,195	3,345	2,947	2,248	(1,169)	811
End of year	18,852	19,038	21,535	16,482	16,217	14,591	19,038	16,217	18,852	16,482	15,047	15,368	16,411
As Previously Reported
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other						(8)
Beginning of year	19,134	21,640	15,126	16,388	14,682	15,432	15,126	15,432	15,126	15,432	15,432	16,518
Net income (loss) attributable to Holdings		(4,028)	5,410	(384)	363	(775)	1,382	(412)		(796)	(1,733)	1,820	834
Other comprehensive income (loss)		1,642	1,441	587	1,388	882	3,083	2,270		2,857	2,232	(1,177)	832
End of year		19,134	21,640	16,478	16,388	14,682	19,134	16,388		16,478	15,126	15,432	16,518
Impact of Revisions
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other						1
Beginning of year	(96)	(105)	(79)	(171)	(91)	(64)	(79)	(64)	(79)	(64)	(64)	(107)
Net income (loss) attributable to Holdings		9	(22)	10	(2)	(30)	(13)	(32)		(22)	(31)	35	(56)
Other comprehensive income (loss)		0	(4)	165	(77)	2	(4)	(75)		90	16	8	(21)
End of year		(96)	(105)	4	(171)	(91)	(96)	(171)		4	(79)	(64)	(107)
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other	0			16	(9)			(16)	20
Beginning of year	1,938		1,920	1,901	1,882	1,908	1,920	1,908	1,920	1,908	1,908
End of year	1,953	1,938		1,897	1,901	1,882	1,938	1,901	1,953	1,897	1,920	1,908
Additional Paid-in Capital | As Previously Reported
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other					(8)			(16)
Beginning of year				1,901	1,881	1,908		1,908		1,908	1,908
End of year					1,901	1,881		1,901				1,908
Additional Paid-in Capital | Impact of Revisions
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other					(1)			0
Beginning of year				0	1	0		0		0	0
End of year					0	1		0				0
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning of year	12,899	17,007	11,744	13,209	12,922	13,937	11,744	13,937	11,744	13,937	13,937	12,138	11,360
Net income (loss) attributable to Holdings		(4,019)	5,388	(374)	361	(805)	1,369	(444)		(818)	(1,764)	1,855	778
End of year	12,032	12,899	17,007	12,761	13,209	12,922	12,899	13,209	12,032	12,761	11,744	13,937	12,138
Retained Earnings | As Previously Reported
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning of year	12,995	17,112	11,827	13,293	13,004	13,989	11,827	13,989	11,827	13,989	13,989	12,225	11,391
Net income (loss) attributable to Holdings		(4,028)	5,410	(384)	363	(775)	1,382	(412)		(796)	(1,733)	1,820	834
End of year		12,995	17,112	12,835	13,293	13,004	12,995	13,293		12,835	11,827	13,989	12,225
Retained Earnings | Impact of Revisions
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning of year	(96)	(105)	(83)	(84)	(82)	(52)	(83)	(52)	(83)	(52)	(52)	(87)	(31)
Net income (loss) attributable to Holdings		9	(22)	10	(2)	(30)	(13)	(32)		(22)	(31)	35	(56)
End of year		(96)	(105)	(74)	(84)	(82)	(96)	(84)		(74)	(83)	(52)	(87)
AOCI Attributable to Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning of year	3,928		844	789	(523)	(1,408)	844	(1,408)	844	(1,408)	(1,408)	(128)	(920)
Other comprehensive income (loss)	260			757	1,312	885		2,197	3,344	2,954	2,252	(1,184)	792
End of year	4,188	3,928		1,546	789	(523)	3,928	789	4,188	1,546	844	(1,408)	(128)
AOCI Attributable to Parent | As Previously Reported
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning of year			840	876	(513)	(1,396)	840	(1,396)	840	(1,396)	(1,396)	(108)	(921)
Other comprehensive income (loss)				592	1,389	883		2,272		2,864	2,236	(1,192)	813
End of year				1,468	876	(513)		876		1,468	840	(1,396)	(108)
AOCI Attributable to Parent | Impact of Revisions
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning of year			4	(87)	(10)	(12)	4	(12)	4	(12)	(12)	(20)	1
Other comprehensive income (loss)				165	(77)	2		(75)		90	16	8	(21)
End of year				78	(87)	(10)		(87)		78	4	(12)	(20)
Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other	0			16					20
Beginning of year	17,498	19,981	13,456	14,672	13,052	13,802	13,456	13,802	13,456	13,802	13,802	13,314
Other comprehensive income (loss)	260			757					3,344	2,954
End of year	17,300	17,498	19,981	14,940	14,672	13,052	17,498	14,672	17,300	14,940	13,456	13,802	13,314
Parent | As Previously Reported
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning of year	17,594	20,086	13,535	14,843	13,143	13,866	13,535	13,866	13,535	13,866	13,866	13,421
End of year		17,594	20,086	14,936	14,843	13,143	17,594	14,843		14,936	13,535	13,866	13,421
Parent | Impact of Revisions
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning of year	$ (96)	(105)	(79)	(171)	(91)	(64)	(79)	(64)	$ (79)	(64)	(64)	(107)
End of year		$ (96)	$ (105)	$ 4	$ (171)	$ (91)	$ (96)	$ (171)		$ 4	$ (79)	$ (64)	$ (107)