Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Series D Preferred Stock	Series E Preferred Stock	Series F Preferred Stock	Series G Preferred Stock	Series H Preferred Stock	Preferred Stock	Common Shares	Capital Surplus	Retained Earnings	Retained Earnings Series D Preferred Stock	Retained Earnings Series E Preferred Stock	Retained Earnings Series F Preferred Stock	Retained Earnings Series G Preferred Stock	Retained Earnings Series H Preferred Stock	Treasury Stock, at Cost	Accumulated Other Comprehensive Income (Loss)
Beginning balance, Preferred Shares (in shares) at Dec. 31, 2022							1,996,000
Beginning balance, Common Shares (in shares) at Dec. 31, 2022								933,325,000
Beginning balance at Dec. 31, 2022	$ 13,454						$ 2,500	$ 1,257	$ 6,286	$ 15,616						$ (5,910)	$ (6,295)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	599									599
Other comprehensive income (loss)	251																251
Deferred compensation	(5)								(5)
Cash dividends declared
Cash dividends declared on common shares	(384)									(384)
Cash dividends declared on preferred stock		$ (13)	$ (15)	$ (12)	$ (13)	$ (19)					$ (13)	$ (15)	$ (12)	$ (13)	$ (19)
Open market Common Share repurchases (in shares)								(2,550,000)
Open market Common Share repurchases	(38)															(38)
Employee equity compensation program Common Share repurchases (in shares)								(1,821,000)
Employee equity compensation program Common Share repurchases	(34)															(34)
Common shares reissued (returned) for stock options and other employee benefit plans (in shares)								6,779,000
Common shares reissued (returned) for stock options and other employee benefit plans	73								(50)							123
Ending balance, Preferred Shares (in shares) at Jun. 30, 2023							1,996,000
Ending balance, Common Shares (in shares) at Jun. 30, 2023								935,733,000
Ending balance at Jun. 30, 2023	13,844						$ 2,500	$ 1,257	6,231	15,759						(5,859)	(6,044)
Beginning balance, Preferred Shares (in shares) at Mar. 31, 2023							1,996,000
Beginning balance, Common Shares (in shares) at Mar. 31, 2023								935,229,000
Beginning balance at Mar. 31, 2023	14,322						$ 2,500	$ 1,257	6,207	15,700						(5,868)	(5,474)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	287									287
Other comprehensive income (loss)	(570)																(570)
Deferred compensation	1								1
Cash dividends declared
Cash dividends declared on common shares	(192)									(192)
Cash dividends declared on preferred stock		(6)	(7)	(6)	(7)	(10)					(6)	(7)	(6)	(7)	(10)
Employee equity compensation program Common Share repurchases (in shares)								(38,000)
Common shares reissued (returned) for stock options and other employee benefit plans (in shares)								542,000
Common shares reissued (returned) for stock options and other employee benefit plans	32								23							9
Ending balance, Preferred Shares (in shares) at Jun. 30, 2023							1,996,000
Ending balance, Common Shares (in shares) at Jun. 30, 2023								935,733,000
Ending balance at Jun. 30, 2023	13,844						$ 2,500	$ 1,257	6,231	15,759						(5,859)	(6,044)
Beginning balance, Preferred Shares (in shares) at Dec. 31, 2023							1,996,000
Beginning balance, Common Shares (in shares) at Dec. 31, 2023								936,564,000
Beginning balance at Dec. 31, 2023	14,637						$ 2,500	$ 1,257	6,281	15,672						(5,844)	(5,229)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	493									493
Other comprehensive income (loss)	85																85
Deferred compensation	(4)								(4)
Cash dividends declared
Cash dividends declared on common shares	(387)									(387)
Cash dividends declared on preferred stock		$ (13)	$ (15)	$ (12)	$ (13)	$ (19)					(13)	(15)	(12)	(13)	(19)
Employee equity compensation program Common Share repurchases (in shares)								(1,879,000)
Employee equity compensation program Common Share repurchases	(26)															(26)
Common shares reissued (returned) for stock options and other employee benefit plans (in shares)								8,515,000
Common shares reissued (returned) for stock options and other employee benefit plans	63								(92)							155
Ending balance, Preferred Shares (in shares) at Jun. 30, 2024		21,000	500,000	425,000	450,000	600,000	1,996,000
Ending balance, Common Shares (in shares) at Jun. 30, 2024								943,200,000
Ending balance at Jun. 30, 2024	14,789						$ 2,500	$ 1,257	6,185	15,706						(5,715)	(5,144)
Beginning balance, Preferred Shares (in shares) at Mar. 31, 2024							1,996,000
Beginning balance, Common Shares (in shares) at Mar. 31, 2024								942,776,000
Beginning balance at Mar. 31, 2024	14,547						$ 2,500	$ 1,257	6,164	15,662						(5,722)	(5,314)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	274									274
Other comprehensive income (loss)	170																170
Cash dividends declared
Cash dividends declared on common shares	(194)									(194)
Cash dividends declared on preferred stock		$ (6)	$ (7)	$ (6)	$ (7)	$ (10)					$ (6)	$ (7)	$ (6)	$ (7)	$ (10)
Employee equity compensation program Common Share repurchases (in shares)								(20,000)
Common shares reissued (returned) for stock options and other employee benefit plans (in shares)								444,000
Common shares reissued (returned) for stock options and other employee benefit plans	28								21							7
Ending balance, Preferred Shares (in shares) at Jun. 30, 2024		21,000	500,000	425,000	450,000	600,000	1,996,000
Ending balance, Common Shares (in shares) at Jun. 30, 2024								943,200,000
Ending balance at Jun. 30, 2024	$ 14,789						$ 2,500	$ 1,257	$ 6,185	$ 15,706						$ (5,715)	$ (5,144)