CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Cumulative effect of period of adoption, adjusted balance	Parent	Parent Cumulative effect of period of adoption, adjusted balance	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative effect of period of adoption, adjusted balance	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Beginning balance at Dec. 31, 2016							$ 6,070		$ (3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	$ 582								582
Ending balance at Dec. 31, 2017	19,395		$ 16,300				8,860		579
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	(1,225)								(1,225)
Ending balance at Dec. 31, 2018	12,359		12,347		$ 2	$ 7,807	5,039		(501)	$ 12
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	765								765
Ending balance at Mar. 31, 2019	12,281		12,269				4,188		264
Beginning balance at Dec. 31, 2018	12,359		12,347		2	7,807	5,039		(501)	12
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	1,991								1,991
Ending balance at Jun. 30, 2019	13,781		13,769		2	7,822	4,455		1,490	12
Beginning balance at Dec. 31, 2018	12,359		12,347		2	7,807	5,039		(501)	12
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividend to parent company	(1,000)						(1,000)
Net income (loss)	(848)		(848)				(848)
Other comprehensive income (loss)	2,721		2,721						2,721
Other	22		22			22
Ending balance at Sep. 30, 2019	13,254		13,242		2	7,829	3,191		2,220	12
Beginning balance at Dec. 31, 2018	12,359		12,347		2	7,807	5,039		(501)	12
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	2,097								2,097
Ending balance at Dec. 31, 2019	11,565	$ (32)	11,552	$ (32)	2	7,809	2,145	$ (32)	1,596	13
Beginning balance at Mar. 31, 2019	12,281		12,269				4,188		264
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	1,226								1,226
Ending balance at Jun. 30, 2019	13,781		13,769		2	7,822	4,455		1,490	12
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividend to parent company	(1,000)						(1,000)
Net income (loss)	(264)		(264)				(264)
Other comprehensive income (loss)	730		730						730
Other	7		7			7
Ending balance at Sep. 30, 2019	13,254		13,242		2	7,829	3,191		2,220	12
Beginning balance at Dec. 31, 2019	11,565	(32)	11,552	(32)	2	7,809	2,145	(32)	1,596	13
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	1,510
Ending balance at Mar. 31, 2020	18,798		18,789				7,870		3,106
Beginning balance at Dec. 31, 2019	11,565	(32)	11,552	(32)	2	7,809	2,145	(32)	1,596	13
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	3,080
Ending balance at Jun. 30, 2020	15,088		15,079		2	7,821	2,580		4,676	9
Beginning balance at Dec. 31, 2019	11,565	$ (32)	11,552	$ (32)	2	7,809	2,145	$ (32)	1,596	13
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividend to parent company	(1,200)		(1,200)				(1,200)			0
Net income (loss)	719		721				721			(2)
Other comprehensive income (loss)	3,327		3,327						3,327
Other	20		22			22				(2)
Ending balance at Sep. 30, 2020	$ 14,399		14,390		2	7,831	1,634		4,923	9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting standards update [extensible list]	us-gaap:AccountingStandardsUpdate201613Member
Beginning balance at Mar. 31, 2020	$ 18,798		18,789				7,870		3,106
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	1,570
Ending balance at Jun. 30, 2020	15,088		15,079		2	7,821	2,580		4,676	9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividend to parent company	0		0				0
Net income (loss)	(946)		(946)				(946)
Other comprehensive income (loss)	247		247						247
Other	10		10			10
Ending balance at Sep. 30, 2020	$ 14,399		$ 14,390		$ 2	$ 7,831	$ 1,634		$ 4,923	$ 9