Unaudited Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Millions	Total	Non-cumulative preferred shares	Common shares	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss), net of deferred income tax	Unrealized appreciation (decline) in value of available-for-sale securities, net of deferred income tax	Foreign currency translation adjustments, net of deferred income tax	Common shares held in treasury, at cost
Balance at beginning of period at Dec. 31, 2023		$ 830	$ 1	$ 2,327	$ 20,295	$ (676)	$ (565)	$ (111)	$ (4,424)
Amortization of share-based compensation				100
Other changes				38
Net income (loss)	$ 3,377				3,377
Preferred share dividends					(30)
Unrealized holding gains (losses) during period, net of reclassification adjustment							500
Foreign currency translation adjustments	(24)							(24)
Shares repurchased for treasury									(40)
Balance at end of period at Sep. 30, 2024	22,274	830	1	2,465	23,642	(200)	(65)	(135)	(4,464)
Balance at beginning of period at Jun. 30, 2024		830	1	2,443	22,664	(810)	(650)	(160)	(4,463)
Amortization of share-based compensation				16
Other changes				6
Net income (loss)	988				988
Preferred share dividends					(10)
Unrealized holding gains (losses) during period, net of reclassification adjustment							585
Foreign currency translation adjustments	25							25
Shares repurchased for treasury									(1)
Balance at end of period at Sep. 30, 2024	22,274	830	1	2,465	23,642	(200)	(65)	(135)	(4,464)
Balance at beginning of period at Dec. 31, 2024	20,820	830	1	2,510	22,686	(720)	(507)	(213)	(4,487)
Amortization of share-based compensation				124
Other changes				48
Net income (loss)	3,161				3,161
Preferred share dividends					(30)
Unrealized holding gains (losses) during period, net of reclassification adjustment							629
Foreign currency translation adjustments	91							91
Shares repurchased for treasury									(1,124)
Balance at end of period at Sep. 30, 2025	23,719	830	1	2,682	25,817	0	122	(122)	(5,611)
Balance at beginning of period at Jun. 30, 2025		830	1	2,660	24,477	(48)	75	(123)	(4,879)
Amortization of share-based compensation				25
Other changes				(3)
Net income (loss)	1,350				1,350
Preferred share dividends					(10)
Unrealized holding gains (losses) during period, net of reclassification adjustment							47
Foreign currency translation adjustments	1							1
Shares repurchased for treasury									(732)
Balance at end of period at Sep. 30, 2025	$ 23,719	$ 830	$ 1	$ 2,682	$ 25,817	$ 0	$ 122	$ (122)	$ (5,611)