Business Segments - Summary on Reconciliation of Results Under IFRS to US GAAP (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022		Mar. 31, 2021	Dec. 31, 2021
Operating Statistics [Line Items]
Net interest income (expense)	$ 477		$ 531
Other operating income	486		384
Total operating income	963		915
Provision for credit losses	11		(227)
Total income	952		1,142
Operating expenses	686		682
Income before income tax	266		460
Total assets	177,016	[1]	194,856	$ 189,232	[1]
Total loans, net	58,143		60,673
Goodwill	458	[1]	458	458	[1]
Total deposits	131,175		148,582	$ 143,032
Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	445		493
Other operating income	528		410
Total operating income (expense)	973		903
Expected credit losses / provision for credit losses	(25)		(91)
Total income	998		994
Operating expenses	665		669
Profit (loss) before income tax	333		325
Total assets	195,493		219,949
Total loans, net	57,105		58,974
Goodwill	358		358
Total deposits	126,419		141,139
Group Reporting Basis Adjustments
Operating Statistics [Line Items]
Net interest income (expense)	1		4
Other operating income	(20)		5
Total operating income (expense)	(19)		9
Expected credit losses / provision for credit losses	36		(136)
Total income	(55)		145
Operating expenses	12		10
Profit (loss) before income tax	(67)		135
Total assets	(18,477)		(25,093)
Total loans, net	(1,566)		(1,367)
Goodwill	100		100
Total deposits	(2,821)		(4,472)
Group Reporting Basis Reclassifications
Operating Statistics [Line Items]
Net interest income (expense)	31		34
Other operating income	(22)		(31)
Total operating income (expense)	9		3
Expected credit losses / provision for credit losses	0		0
Total income	9		3
Operating expenses	9		3
Profit (loss) before income tax	0		0
Total assets	0		0
Total loans, net	2,604		3,066
Goodwill	0		0
Total deposits	7,577		11,915
WPB | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	169		209
Other operating income	163		87
Total operating income (expense)	332		296
Expected credit losses / provision for credit losses	4		(2)
Total income	328		298
Operating expenses	242		287
Profit (loss) before income tax	86		11
Total assets	46,143		63,747
Total loans, net	21,675		24,513
Goodwill	0		0
Total deposits	40,217		49,578
CMB | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	185		190
Other operating income	83		66
Total operating income (expense)	268		256
Expected credit losses / provision for credit losses	(27)		(38)
Total income	295		294
Operating expenses	147		150
Profit (loss) before income tax	148		144
Total assets	52,519		44,170
Total loans, net	23,484		22,785
Goodwill	358		358
Total deposits	40,746		42,874
GB
Operating Statistics [Line Items]
Profit (loss) before income tax			144
Total assets			11,284
Total deposits			44,768
GB | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	78		83
Other operating income	124		105
Total operating income (expense)	202		188
Expected credit losses / provision for credit losses	(2)		(50)
Total income	204		238
Operating expenses	117		94
Profit (loss) before income tax	87		144
Total assets	10,988		11,284
Total loans, net	10,533		10,869
Goodwill	0		0
Total deposits	43,355		44,768
MSS
Operating Statistics [Line Items]
Profit (loss) before income tax			48
Total assets			55,433
Total deposits			2,220
MSS | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	16		13
Other operating income	142		116
Total operating income (expense)	158		129
Expected credit losses / provision for credit losses	0		0
Total income	158		129
Operating expenses	69		81
Profit (loss) before income tax	89		48
Total assets	39,648		55,433
Total loans, net	194		149
Goodwill	0		0
Total deposits	1,358		2,220
GBM Other
Operating Statistics [Line Items]
Profit (loss) before income tax			(1)
Total assets			43,807
Total deposits			1,699
GBM Other | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	(2)		(1)
Other operating income	24		25
Total operating income (expense)	22		24
Expected credit losses / provision for credit losses	0		(1)
Total income	22		25
Operating expenses	24		26
Profit (loss) before income tax	(2)		(1)
Total assets	44,165		43,807
Total loans, net	1,219		658
Goodwill	0		0
Total deposits	743		1,699
CC | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	(1)		(1)
Other operating income	(8)		11
Total operating income (expense)	(9)		10
Expected credit losses / provision for credit losses	0		0
Total income	(9)		10
Operating expenses	66		31
Profit (loss) before income tax	(75)		(21)
Total assets	2,030		1,508
Total loans, net	0		0
Goodwill	0		0
Total deposits	$ 0		$ 0

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at March 31, 2022 and December 31, 2021. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 17, "Variable Interest Entities," for additional information. March 31, 2022December 31, 2021(in millions)AssetsLoans$128 $46 Other assets51 55 Total assets$179 $101 LiabilitiesInterest, taxes and other liabilities$31 $9 Total liabilities$31 $9