Loans - Summary of Criticized Assets for Commercial Loans (Detail) - USD ($) $ in Millions		Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Total	[1]	$ 57,945	$ 59,380
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		1,010	4,748
One year prior to current year		4,165	2,485
Two years prior to current year		2,697	1,814
Three years prior to current year		1,579	3,109
Four years prior to current year		2,800	2,311
Prior		12,750	11,997
Revolving Loans		14,533	15,143
Revolving Loans Converted to Term Loans		277	210
Total		39,811	41,817
Commercial loans | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		56	1,315
One year prior to current year		1,262	854
Two years prior to current year		960	520
Three years prior to current year		388	1,714
Four years prior to current year		1,524	1,803
Prior		2,951	1,712
Revolving Loans		41	42
Revolving Loans Converted to Term Loans		3	3
Total		7,185	7,963
Commercial loans | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		490	1,116
One year prior to current year		1,103	828
Two years prior to current year		837	475
Three years prior to current year		328	815
Four years prior to current year		647	308
Prior		4,784	5,019
Revolving Loans		7,706	7,307
Revolving Loans Converted to Term Loans		274	207
Total		16,169	16,075
Commercial loans | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		448	2,034
One year prior to current year		1,512	449
Two years prior to current year		610	212
Three years prior to current year		162	177
Four years prior to current year		209	114
Prior		4,105	4,152
Revolving Loans		3,081	3,440
Revolving Loans Converted to Term Loans		0	0
Total		10,127	10,578
Commercial loans | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		16	283
One year prior to current year		288	354
Two years prior to current year		290	607
Three years prior to current year		701	403
Four years prior to current year		420	86
Prior		910	1,114
Revolving Loans		3,705	4,354
Revolving Loans Converted to Term Loans		0	0
Total		6,330	7,201
Commercial loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		2	472
One year prior to current year		347	43
Two years prior to current year		72	121
Three years prior to current year		116	294
Four years prior to current year		335	763
Prior		1,688	1,174
Revolving Loans		1,217	1,233
Revolving Loans Converted to Term Loans		4	8
Total		3,781	4,108
Commercial loans | Criticized | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	205
One year prior to current year		96	0
Two years prior to current year		0	70
Three years prior to current year		70	276
Four years prior to current year		320	704
Prior		1,200	910
Revolving Loans		72	82
Revolving Loans Converted to Term Loans		3	3
Total		1,761	2,250
Commercial loans | Criticized | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	4
One year prior to current year		33	43
Two years prior to current year		72	51
Three years prior to current year		46	2
Four years prior to current year		0	59
Prior		344	254
Revolving Loans		1,051	754
Revolving Loans Converted to Term Loans		1	5
Total		1,547	1,172
Commercial loans | Criticized | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		2	232
One year prior to current year		218	0
Two years prior to current year		0	0
Three years prior to current year		0	16
Four years prior to current year		15	0
Prior		128	10
Revolving Loans		82	383
Revolving Loans Converted to Term Loans		0	0
Total		445	641
Commercial loans | Criticized | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	31
One year prior to current year		0	0
Two years prior to current year		0	0
Three years prior to current year		0	0
Four years prior to current year		0	0
Prior		16	0
Revolving Loans		12	14
Revolving Loans Converted to Term Loans		0	0
Total		28	45
Commercial loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		2	205
One year prior to current year		116	0
Two years prior to current year		0	38
Three years prior to current year		79	213
Four years prior to current year		263	61
Prior		256	143
Revolving Loans		430	427
Revolving Loans Converted to Term Loans		3	3
Total		1,149	1,090
Commercial loans | Special mention | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	204
One year prior to current year		96	0
Two years prior to current year		0	22
Three years prior to current year		69	212
Four years prior to current year		263	27
Prior		65	19
Revolving Loans		54	63
Revolving Loans Converted to Term Loans		3	3
Total		550	550
Commercial loans | Special mention | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	1
One year prior to current year		20	0
Two years prior to current year		0	16
Three years prior to current year		10	1
Four years prior to current year		0	34
Prior		191	116
Revolving Loans		353	182
Revolving Loans Converted to Term Loans		0	0
Total		574	350
Commercial loans | Special mention | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		2	0
One year prior to current year		0	0
Two years prior to current year		0	0
Three years prior to current year		0	0
Four years prior to current year		0	0
Prior		0	8
Revolving Loans		23	182
Revolving Loans Converted to Term Loans		0	0
Total		25	190
Commercial loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	236
One year prior to current year		231	43
Two years prior to current year		0	74
Three years prior to current year		28	81
Four years prior to current year		72	687
Prior		1,318	1,031
Revolving Loans		720	760
Revolving Loans Converted to Term Loans		1	1
Total		2,370	2,913
Commercial loans | Substandard | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	1
One year prior to current year		0	0
Two years prior to current year		0	48
Three years prior to current year		1	64
Four years prior to current year		57	677
Prior		1,071	891
Revolving Loans		18	19
Revolving Loans Converted to Term Loans		0	0
Total		1,147	1,700
Commercial loans | Substandard | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	3
One year prior to current year		13	43
Two years prior to current year		0	26
Three years prior to current year		27	1
Four years prior to current year		0	10
Prior		145	138
Revolving Loans		655	548
Revolving Loans Converted to Term Loans		1	1
Total		841	770
Commercial loans | Substandard | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	232
One year prior to current year		218	0
Two years prior to current year		0	0
Three years prior to current year		0	16
Four years prior to current year		15	0
Prior		99	2
Revolving Loans		47	186
Revolving Loans Converted to Term Loans		0	0
Total		379	436
Commercial loans | Substandard | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	0
One year prior to current year		0	0
Two years prior to current year		0	0
Three years prior to current year		0	0
Four years prior to current year		0	0
Prior		3	0
Revolving Loans		0	7
Revolving Loans Converted to Term Loans		0	0
Total		3	7
Commercial loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	31
One year prior to current year		0	0
Two years prior to current year		72	9
Three years prior to current year		9	0
Four years prior to current year		0	15
Prior		114	0
Revolving Loans		67	46
Revolving Loans Converted to Term Loans		0	4
Total		262	105
Commercial loans | Doubtful | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0
One year prior to current year		0
Two years prior to current year		0
Three years prior to current year		0
Four years prior to current year		0
Prior		64
Revolving Loans		0
Revolving Loans Converted to Term Loans		0
Total		64
Commercial loans | Doubtful | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	0
One year prior to current year		0	0
Two years prior to current year		72	9
Three years prior to current year		9	0
Four years prior to current year		0	15
Prior		8	0
Revolving Loans		43	24
Revolving Loans Converted to Term Loans		0	4
Total		132	52
Commercial loans | Doubtful | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	0
One year prior to current year		0	0
Two years prior to current year		0	0
Three years prior to current year		0	0
Four years prior to current year		0	0
Prior		29	0
Revolving Loans		12	15
Revolving Loans Converted to Term Loans		0	0
Total		41	15
Commercial loans | Doubtful | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	31
One year prior to current year		0	0
Two years prior to current year		0	0
Three years prior to current year		0	0
Four years prior to current year		0	0
Prior		13	0
Revolving Loans		12	7
Revolving Loans Converted to Term Loans		0	0
Total		$ 25	$ 38

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at June 30, 2023 and December 31, 2022. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 17, "Variable Interest Entities," for additional information. June 30, 2023December 31, 2022(in millions)AssetsLoans, net$186 $162 Other assets40 44 Total assets$226 $206 LiabilitiesInterest, taxes and other liabilities$35 $22 Total liabilities$35 $22