Business Segments - Summary on Reconciliation of Results Under IFRS to US GAAP (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Operating Statistics [Line Items]
Net interest income (expense)	$ 2,083		$ 2,174		$ 2,112
Other operating income	1,237		1,535		1,854
Total operating income	3,320		3,709		3,966
Provision for credit losses	(570)		810		195
Total income	3,890		2,899		3,771
Operating expenses	2,978		3,881		3,501
Income (loss) before income tax	912		(982)		270
Total assets	189,232	[1]	196,434	[1]	175,375
Total loans, net	55,417		61,073		67,916
Goodwill	458	[1]	458	[1]	1,242
Total deposits	143,032		145,150		119,693
Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	1,904		2,026		2,303
Other operating income	1,430		1,701		1,537
Total operating income (expense)	3,334		3,727		3,840
Expected credit losses / provision for credit losses	(205)		622		171
Total income	3,539		3,105		3,669
Operating expenses	2,898		4,034		3,313
Profit (loss) before income tax	641		(929)		356
Total assets	205,346		229,677		214,223
Total loans, net	55,245		59,489		66,449
Goodwill	358		358		1,051
Total deposits	128,936		137,037		103,589
Group Reporting Basis Adjustments
Operating Statistics [Line Items]
Net interest income (expense)	19		9		13
Other operating income	(51)		(46)		102
Total operating income (expense)	(32)		(37)		115
Expected credit losses / provision for credit losses	(365)		188		32
Total income	333		(225)		83
Operating expenses	62		(172)		169
Profit (loss) before income tax	271		(53)		(86)
Total assets	(16,114)		(33,243)		(38,848)
Total loans, net	(1,991)		(2,307)		(2,965)
Goodwill	100		100		191
Total deposits	(2,889)		(4,253)		(4,747)
Group Reporting Basis Reclassifications
Operating Statistics [Line Items]
Net interest income (expense)	160		139		(204)
Other operating income	(142)		(120)		215
Total operating income (expense)	18		19		11
Expected credit losses / provision for credit losses	0		0		(8)
Total income	18		19		19
Operating expenses	18		19		19
Profit (loss) before income tax	0		0		0
Total assets	0		0		0
Total loans, net	2,163		3,891		4,432
Goodwill	0		0		0
Total deposits	16,985		12,366		20,851
WPB
Operating Statistics [Line Items]
Goodwill					737
WPB | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	801		837		1,018
Other operating income	303		368		330
Total operating income (expense)	1,104		1,205		1,348
Expected credit losses / provision for credit losses	(21)		189		115
Total income	1,125		1,016		1,233
Operating expenses	1,221		2,203		1,645
Profit (loss) before income tax	(96)		(1,187)		(412)
Total assets	62,904		59,200		50,851
Total loans, net	22,285		24,048		24,243
Goodwill	0		0		693
Total deposits	40,232		50,000		44,553
CMB | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	771		821		829
Other operating income	297		234		239
Total operating income (expense)	1,068		1,055		1,068
Expected credit losses / provision for credit losses	(26)		293		55
Total income	1,094		762		1,013
Operating expenses	581		587		581
Profit (loss) before income tax	513		175		432
Total assets	43,052		36,354		34,241
Total loans, net	21,971		23,377		24,647
Goodwill	358		358		358
Total deposits	45,082		42,369		29,986
GB
Operating Statistics [Line Items]
Profit (loss) before income tax			209		544
Total assets			11,473		16,002
Total deposits			37,320		24,596
GB | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	315		369		513
Other operating income	409		351		415
Total operating income (expense)	724		720		928
Expected credit losses / provision for credit losses	(157)		139		1
Total income	881		581		927
Operating expenses	407		372		383
Profit (loss) before income tax	474		209		544
Total assets	10,486		11,473		16,002
Total loans, net	9,930		11,260		15,875
Goodwill	0		0		0
Total deposits	41,343		37,320		24,596
MSS
Operating Statistics [Line Items]
Profit (loss) before income tax			194		132
Total assets			67,293		71,742
Total deposits			3,417		2,956
MSS | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	47		91		91
Other operating income	318		454		358
Total operating income (expense)	365		545		449
Expected credit losses / provision for credit losses	0		0		0
Total income	365		545		449
Operating expenses	275		351		317
Profit (loss) before income tax	90		194		132
Total assets	43,007		67,293		71,742
Total loans, net	178		329		777
Goodwill	0		0		0
Total deposits	1,298		3,417		2,956
GBM Other
Operating Statistics [Line Items]
Profit (loss) before income tax			(16)		(105)
Total assets			53,597		38,966
Total deposits			3,931		1,498
GBM Other | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	(24)		(62)		(83)
Other operating income	100		165		127
Total operating income (expense)	76		103		44
Expected credit losses / provision for credit losses	(1)		1		0
Total income	77		102		44
Operating expenses	98		118		149
Profit (loss) before income tax	(21)		(16)		(105)
Total assets	44,151		53,597		38,966
Total loans, net	881		475		907
Goodwill	0		0		0
Total deposits	981		3,931		1,498
CC | Operating Segments
Operating Statistics [Line Items]
Net interest income (expense)	(6)		(30)		(65)
Other operating income	3		129		68
Total operating income (expense)	(3)		99		3
Expected credit losses / provision for credit losses	0		0		0
Total income	(3)		99		3
Operating expenses	316		403		238
Profit (loss) before income tax	(319)		(304)		(235)
Total assets	1,746		1,760		2,421
Total loans, net	0		0		0
Goodwill	0		0		0
Total deposits	$ 0		$ 0		$ 0

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at December 31, 2021 and 2020. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 27, "Variable Interest Entities," for additional information. At December 31,20212020(in millions)AssetsLoans$46 $10 Other assets55 79 Total assets$101 $89 LiabilitiesInterest, taxes and other liabilities$9 $10 Total liabilities$9 $10