Business Segments - Summary on Reconciliation of Results Under IFRS to US GAAP (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2024		Sep. 30, 2023	Sep. 30, 2024		Sep. 30, 2023	Dec. 31, 2023	[1]
Operating Statistics [Line Items]
Net interest income (expense)	$ 439		$ 372	$ 1,277		$ 1,289
Other operating income (expense)	334		517	1,410		1,418
Total operating income (expense)	773		889	2,687		2,707
Provision for credit losses	(13)		(8)	36		48
Total income	786		897	2,651		2,659
Operating expenses	671		658	2,040		1,934
Income before income tax	115		239	611		725
Total assets	167,799	[1]	164,357	167,799	[1]	164,357	$ 168,238
Total loans, net	61,467	[1]	57,016	61,467	[1]	57,016	58,396
Goodwill	458	[1]	458	458	[1]	458	458
Total deposits	123,373	[1]	119,928	123,373	[1]	119,928	$ 121,283
Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	451		432	1,328		1,477
Other operating income (expense)	313		446	1,324		1,236
Total operating income	764		878	2,652		2,713
Expected credit losses / provision for credit losses	19		(15)	52		47
Total income	745		893	2,600		2,666
Operating expenses	654		636	1,997		1,687
Profit (loss) before income tax	91		257	603		979
Total assets	181,011		186,442	181,011		186,442
Total loans, net	59,851		55,804	59,851		55,804
Goodwill	358		358	358		358
Total deposits	115,774		115,504	115,774		115,504
Group Reporting Basis Adjustments
Operating Statistics [Line Items]
Net interest income (expense)	9		1	22		4
Other operating income (expense)	(7)		(8)	(13)		(57)
Total operating income	2		(7)	9		(53)
Expected credit losses / provision for credit losses	(32)		7	(16)		1
Total income	34		(14)	25		(54)
Operating expenses	10		4	17		200
Profit (loss) before income tax	24		(18)	8		(254)
Total assets	(13,212)		(22,085)	(13,212)		(22,085)
Total loans, net	(1,054)		(313)	(1,054)		(313)
Goodwill	100		100	100		100
Total deposits	(1,192)		(3,853)	(1,192)		(3,853)
Group Reporting Basis Reclassifications
Operating Statistics [Line Items]
Net interest income (expense)	(21)		(61)	(73)		(192)
Other operating income (expense)	28		79	99		239
Total operating income	7		18	26		47
Expected credit losses / provision for credit losses	0		0	0		0
Total income	7		18	26		47
Operating expenses	7		18	26		47
Profit (loss) before income tax	0		0	0		0
Total assets	0		0	0		0
Total loans, net	2,670		1,525	2,670		1,525
Goodwill	0		0	0		0
Total deposits	8,791		8,277	8,791		8,277
WPB | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	175		175	529		582
Other operating income (expense)	8		28	133		132
Total operating income	183		203	662		714
Expected credit losses / provision for credit losses	2		(5)	0		(3)
Total income	181		208	662		717
Operating expenses	207		194	592		420
Profit (loss) before income tax	(26)		14	70		297
Total assets	38,385		42,719	38,385		42,719
Total loans, net	25,785		23,178	25,785		23,178
Goodwill	0		0	0		0
Total deposits	28,903		29,253	28,903		29,253
CMB | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	305		285	884		858
Other operating income (expense)	29		74	189		225
Total operating income	334		359	1,073		1,083
Expected credit losses / provision for credit losses	21		8	56		38
Total income	313		351	1,017		1,045
Operating expenses	187		175	555		484
Profit (loss) before income tax	126		176	462		561
Total assets	54,909		52,215	54,909		52,215
Total loans, net	24,045		23,119	24,045		23,119
Goodwill	358		358	358		358
Total deposits	43,333		44,948	43,333		44,948
GB | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	136		111	369		373
Other operating income (expense)	78		92	266		238
Total operating income	214		203	635		611
Expected credit losses / provision for credit losses	(4)		(18)	(4)		12
Total income	218		221	639		599
Operating expenses	133		144	398		420
Profit (loss) before income tax	85		77	241		179
Total assets	10,122		9,554	10,122		9,554
Total loans, net	9,828		9,009	9,828		9,009
Goodwill	0		0	0		0
Total deposits	40,881		38,810	40,881		38,810
MSS | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	13		4	30		32
Other operating income (expense)	72		115	231		261
Total operating income	85		119	261		293
Expected credit losses / provision for credit losses	0		0	0		0
Total income	85		119	261		293
Operating expenses	78		68	238		208
Profit (loss) before income tax	7		51	23		85
Total assets	35,264		42,663	35,264		42,663
Total loans, net	117		104	117		104
Goodwill	0		0	0		0
Total deposits	1,393		825	1,393		825
GBM Other | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	(3)		(9)	18		(21)
Other operating income (expense)	(48)		17	(2)		63
Total operating income	(51)		8	16		42
Expected credit losses / provision for credit losses	0		0	0		0
Total income	(51)		8	16		42
Operating expenses	25		19	72		51
Profit (loss) before income tax	(76)		(11)	(56)		(9)
Total assets	38,053		36,303	38,053		36,303
Total loans, net	76		394	76		394
Goodwill	0		0	0		0
Total deposits	1,264		1,668	1,264		1,668
CC | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	(175)		(134)	(502)		(347)
Other operating income (expense)	174		120	507		317
Total operating income	(1)		(14)	5		(30)
Expected credit losses / provision for credit losses	0		0	0		0
Total income	(1)		(14)	5		(30)
Operating expenses	24		36	142		104
Profit (loss) before income tax	(25)		(50)	(137)		(134)
Total assets	4,278		2,988	4,278		2,988
Total loans, net	0		0	0		0
Goodwill	0		0	0		0
Total deposits	$ 0		$ 0	$ 0		$ 0

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at September 30, 2024 and December 31, 2023. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 15, "Variable Interest Entities," for additional information. September 30, 2024December 31, 2023(in millions)AssetsOther assets$13 $23 Total assets$13 $23 LiabilitiesInterest, taxes and other liabilities$21 $17 Total liabilities$21 $17