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)	(10,144)					(10,144)
Other comprehensive income (loss), net of tax	(91)						(91)
Dividends on common stock	(727)					(727)
Dividends on preferred stock	(219)		3		219	(441)
Stock warrants issued	107				870	(763)
Issuance of common stock and other, net	192		1		191
Purchases of treasury stock	(4)			(4)
Ending balance at Jun. 30, 2020	23,346	9,762	213	(10,657)	16,235	8,105	(312)
Beginning balance at Mar. 31, 2020	31,295	9,762	210	(10,653)	15,081	17,229	(334)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(8,131)					(8,131)
Other comprehensive income (loss), net of tax	22						22
Dividends on common stock	(8)					(8)
Dividends on preferred stock	0		3		219	(222)
Stock warrants issued	107				870	(763)
Issuance of common stock and other, net	65				65
Purchases of treasury stock	(4)			(4)
Ending balance at Jun. 30, 2020	23,346	9,762	213	(10,657)	16,235	8,105	(312)
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)	(43)					(43)
Other comprehensive income (loss), net of tax	50						50
Dividends on common stock	(20)					(20)
Dividends on preferred stock	(400)					(400)
Issuance of common stock and other, net	87		1		86
Purchases of treasury stock	(3)			(3)
Ending balance at Jun. 30, 2021	18,244	9,762	217	(10,668)	16,638	2,533	(238)
Beginning balance at Mar. 31, 2021	18,300	9,762	217	(10,668)	16,585	2,639	(235)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	103					103
Other comprehensive income (loss), net of tax	(3)						(3)
Dividends on common stock	(9)					(9)
Dividends on preferred stock	(200)					(200)
Issuance of common stock and other, net	53				53
Ending balance at Jun. 30, 2021	$ 18,244	$ 9,762	$ 217	$ (10,668)	$ 16,638	$ 2,533	$ (238)