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 loss	(2,013)					(2,013)
Other comprehensive income (loss), net of tax	(113)						(113)
Dividends on common stock	(719)					(719)
Dividends on preferred stock	(219)					(219)
Issuance of common stock and other, net	127		1		126
Ending balance at Mar. 31, 2020	31,295	9,762	210	(10,653)	15,081	17,229	(334)
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 loss	(146)					(146)
Other comprehensive income (loss), net of tax	53						53
Dividends on common stock	(11)					(11)
Dividends on preferred stock	(200)					(200)
Shareholder warrants exercised	3				3
Issuance of common stock and other, net	31		1		30
Purchases of treasury stock	(3)			(3)
Ending balance at Mar. 31, 2021	$ 18,300	$ 9,762	$ 217	$ (10,668)	$ 16,585	$ 2,639	$ (235)