CONSOLIDATED CONDENSED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2019	$ 34,232	$ 9,762	$ 209	$ (10,653)	$ 14,955	$ 20,180	$ (221)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(13,719)					(13,719)
Other comprehensive income (loss), net of tax	(62)						(62)
Dividends on common stock	(737)					(737)
Dividends on preferred stock	(200)		6		438	(644)
Stock warrants issued	107				870	(763)
Issuance of common stock and other, net	243		1		242
Purchases of treasury stock	(4)			(4)
Ending balance at Sep. 30, 2020	19,860	9,762	216	(10,657)	16,505	4,317	(283)
Beginning balance at Jun. 30, 2020	23,346	9,762	213	(10,657)	16,235	8,105	(312)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(3,575)					(3,575)
Other comprehensive income (loss), net of tax	29						29
Dividends on common stock	(10)					(10)
Dividends on preferred stock	19		3		219	(203)
Issuance of common stock and other, net	51				51
Ending balance at Sep. 30, 2020	19,860	9,762	216	(10,657)	16,505	4,317	(283)
Beginning balance at Dec. 31, 2020	18,573	9,762	216	(10,665)	16,552	2,996	(288)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	785					785
Other comprehensive income (loss), net of tax	6						6
Dividends on common stock	(29)					(29)
Dividends on preferred stock	(600)					(600)
Issuance of common stock and other, net	141		1		140
Purchases of treasury stock	(3)			(3)
Ending balance at Sep. 30, 2021	18,873	9,762	217	(10,668)	16,692	3,152	(282)
Beginning balance at Jun. 30, 2021	18,244	9,762	217	(10,668)	16,638	2,533	(238)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	828					828
Other comprehensive income (loss), net of tax	(44)						(44)
Dividends on common stock	(9)					(9)
Dividends on preferred stock	(200)					(200)
Issuance of common stock and other, net	54				54
Ending balance at Sep. 30, 2021	$ 18,873	$ 9,762	$ 217	$ (10,668)	$ 16,692	$ 3,152	$ (282)