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, 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)	83									83
Other comprehensive income (loss)	1,948																1,948
Deferred compensation	(4)								(4)
Cash dividends declared
Cash dividends declared on common shares	(581)									(581)
Cash dividends declared on preferred stock		$ (20)	$ (23)	$ (18)	$ (19)	$ (28)					$ (20)	$ (23)	$ (18)	$ (19)	$ (28)
Employee equity compensation program Common Share repurchases (in shares)								(1,887,000)
Employee equity compensation program Common Share repurchases	(27)															(27)
Common Shares reissued (returned) for stock options and other employee benefit plans (in shares)								8,745,000
Common Shares reissued (returned) for stock options and other employee benefit plans	93								(67)							160
Common Shares reissued under Scotiabank investment agreement, net of issuance costs (in shares)								47,829,000
Common Shares reissued under Scotiabank investment agreement, net of issuance costs	811								(61)							872
Ending balance, Preferred Shares (in shares) at Sep. 30, 2024							1,996,000
Ending balance, Common Shares (in shares) at Sep. 30, 2024								991,251,000
Ending balance at Sep. 30, 2024	16,852						$ 2,500	$ 1,257	6,149	15,066						(4,839)	(3,281)
Beginning balance, Preferred Shares (in shares) at Jun. 30, 2024							1,996,000
Beginning balance, Common Shares (in shares) at Jun. 30, 2024								943,200,000
Beginning balance at Jun. 30, 2024	14,789						$ 2,500	$ 1,257	6,185	15,706						(5,715)	(5,144)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(410)									(410)
Other comprehensive income (loss)	1,863																1,863
Cash dividends declared
Cash dividends declared on common shares	(194)									(194)
Cash dividends declared on preferred stock		(7)	(8)	(6)	(6)	(9)					(7)	(8)	(6)	(6)	(9)
Employee equity compensation program Common Share repurchases (in shares)								(8,000)
Employee equity compensation program Common Share repurchases	(1)															(1)
Common Shares reissued (returned) for stock options and other employee benefit plans (in shares)								230,000
Common Shares reissued (returned) for stock options and other employee benefit plans	30								25							5
Common Shares reissued under Scotiabank investment agreement, net of issuance costs (in shares)								47,829,000
Common Shares reissued under Scotiabank investment agreement, net of issuance costs	811								(61)							872
Ending balance, Preferred Shares (in shares) at Sep. 30, 2024							1,996,000
Ending balance, Common Shares (in shares) at Sep. 30, 2024								991,251,000
Ending balance at Sep. 30, 2024	16,852						$ 2,500	$ 1,257	6,149	15,066						(4,839)	(3,281)
Beginning balance, Preferred Shares (in shares) at Dec. 31, 2024							1,996,000
Beginning balance, Common Shares (in shares) at Dec. 31, 2024								1,106,786,000
Beginning balance at Dec. 31, 2024	18,176						$ 2,500	$ 1,257	6,038	14,584						(2,733)	(3,470)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,319									1,319
Other comprehensive income (loss)	1,321																1,321
Deferred compensation	(1)								(1)
Cash dividends declared
Cash dividends declared on common shares	(684)									(684)
Cash dividends declared on preferred stock		$ (20)	$ (23)	$ (18)	$ (19)	$ (28)					(20)	(23)	(18)	(19)	(28)
Employee equity compensation program Common Share repurchases (in shares)								(1,963,000)
Employee equity compensation program Common Share repurchases	(35)															(35)
Common Shares reissued (returned) for stock options and other employee benefit plans (in shares)								8,129,000
Common Shares reissued (returned) for stock options and other employee benefit plans	114								(35)							149
Ending balance, Preferred Shares (in shares) at Sep. 30, 2025		21,000	500,000	425,000	450,000	600,000	1,996,000
Ending balance, Common Shares (in shares) at Sep. 30, 2025								1,112,952,000
Ending balance at Sep. 30, 2025	20,102						$ 2,500	$ 1,257	6,002	15,111						(2,619)	(2,149)
Beginning balance, Preferred Shares (in shares) at Jun. 30, 2025							1,996,000
Beginning balance, Common Shares (in shares) at Jun. 30, 2025								1,112,453,000
Beginning balance at Jun. 30, 2025	19,484						$ 2,500	$ 1,257	5,971	14,886						(2,629)	(2,501)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	489									489
Other comprehensive income (loss)	352																352
Cash dividends declared
Cash dividends declared on common shares	(228)									(228)
Cash dividends declared on preferred stock		$ (7)	$ (8)	$ (6)	$ (6)	$ (9)					$ (7)	$ (8)	$ (6)	$ (6)	$ (9)
Employee equity compensation program Common Share repurchases (in shares)								(1,000)
Common Shares reissued (returned) for stock options and other employee benefit plans (in shares)								500,000
Common Shares reissued (returned) for stock options and other employee benefit plans	41								31							10
Ending balance, Preferred Shares (in shares) at Sep. 30, 2025		21,000	500,000	425,000	450,000	600,000	1,996,000
Ending balance, Common Shares (in shares) at Sep. 30, 2025								1,112,952,000
Ending balance at Sep. 30, 2025	$ 20,102						$ 2,500	$ 1,257	$ 6,002	$ 15,111						$ (2,619)	$ (2,149)