Consolidated Statements Of Equity - USD ($) $ in Millions	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]	Noncontrolling Interests [Member] Preferred Stock [Member]
Balance at Dec. 31, 2015	$ 40,323		$ 15	$ 27,607	$ 20,285	$ (8,036)	$ 452
Net income (loss)	9,268				9,427		(159)
Other comprehensive income (loss)	(1,353)					(1,294)	(59)
Issuance of common stock	290			290
Purchase of common stock	(2,500)		0	(1,320)	(1,180)
Exercise of common stock warrants	89			89
Stock based compensation	290			317	(27)
Cash dividends paid on common stock	(2,337)				(2,337)
Dividends to noncontrolling interests	(31)						(31)
Other	36						36
Balance at Dec. 31, 2016	44,075		15	26,983	26,168	(9,330)	239
Net income (loss)	(3,882)				(3,864)		(18)
Other comprehensive income (loss)	1,317					1,319	(2)
Issuance of common stock		$ 985						$ 985
Purchase of common stock	(4,492)		(1)	(2,063)	(2,428)
Exercise of common stock warrants	43			43
Stock based compensation	434			468	(34)
Cash dividends paid on common stock	(2,215)				(2,215)
Dividends to noncontrolling interests	(18)						(18)
Other	(47)			(60)			13
Balance at Dec. 31, 2017	36,200		14	25,371	17,627	(8,011)	1,199
Adoption of accounting standards (Note 2)	(1,144)				(1,046)	(98)
Net income (loss)	8,005				8,014		(9)
Other comprehensive income (loss)	(936)					(930)	(6)
Issuance of common stock		$ 2,862						$ 2,862
Purchase of common stock	(190)		0	(91)	(99)
Stock based compensation	287			287	0
Cash dividends paid on common stock	(2,144)				(2,144)
Dividends to noncontrolling interests	(169)						(169)
Other	6			(4)	(30)		40
Balance at Dec. 31, 2018	$ 42,777		$ 14	$ 25,563	$ 22,322	$ (9,039)	$ 3,917