Loans - Summary of Criticized Assets for Commercial Loans (Detail) - USD ($) $ in Millions		Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Total	[1]	$ 58,987	$ 59,380
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		4,656	4,748
One year prior to current year		3,868	2,485
Two years prior to current year		3,250	1,814
Three years prior to current year		1,388	3,109
Four years prior to current year		2,354	2,311
Prior		11,069	11,997
Revolving Loans		13,054	15,143
Revolving Loans Converted to Term Loans		318	210
Total		39,957	41,817
Commercial loans | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		920	1,315
One year prior to current year		1,286	854
Two years prior to current year		1,019	520
Three years prior to current year		355	1,714
Four years prior to current year		1,054	1,803
Prior		2,409	1,712
Revolving Loans		41	42
Revolving Loans Converted to Term Loans		3	3
Total		7,087	7,963
Commercial loans | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		1,270	1,116
One year prior to current year		1,148	828
Two years prior to current year		1,074	475
Three years prior to current year		231	815
Four years prior to current year		561	308
Prior		4,253	5,019
Revolving Loans		6,922	7,307
Revolving Loans Converted to Term Loans		265	207
Total		15,724	16,075
Commercial loans | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		2,255	2,034
One year prior to current year		1,153	449
Two years prior to current year		844	212
Three years prior to current year		151	177
Four years prior to current year		321	114
Prior		3,600	4,152
Revolving Loans		2,351	3,440
Revolving Loans Converted to Term Loans		50	0
Total		10,725	10,578
Commercial loans | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		211	283
One year prior to current year		281	354
Two years prior to current year		313	607
Three years prior to current year		651	403
Four years prior to current year		418	86
Prior		807	1,114
Revolving Loans		3,740	4,354
Revolving Loans Converted to Term Loans		0	0
Total		6,421	7,201
Commercial loans | Criticized
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		115	472
One year prior to current year		366	43
Two years prior to current year		48	121
Three years prior to current year		136	294
Four years prior to current year		126	763
Prior		1,479	1,174
Revolving Loans		1,273	1,233
Revolving Loans Converted to Term Loans		12	8
Total		3,555	4,108
Commercial loans | Criticized | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		2	205
One year prior to current year		40	0
Two years prior to current year		0	70
Three years prior to current year		105	276
Four years prior to current year		92	704
Prior		1,029	910
Revolving Loans		21	82
Revolving Loans Converted to Term Loans		3	3
Total		1,292	2,250
Commercial loans | Criticized | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		69	4
One year prior to current year		125	43
Two years prior to current year		48	51
Three years prior to current year		31	2
Four years prior to current year		20	59
Prior		291	254
Revolving Loans		1,113	754
Revolving Loans Converted to Term Loans		9	5
Total		1,706	1,172
Commercial loans | Criticized | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	232
One year prior to current year		201	0
Two years prior to current year		0	0
Three years prior to current year		0	16
Four years prior to current year		14	0
Prior		159	10
Revolving Loans		136	383
Revolving Loans Converted to Term Loans		0	0
Total		510	641
Commercial loans | Criticized | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		44	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		0	0
Revolving Loans		3	14
Revolving Loans Converted to Term Loans		0	0
Total		47	45
Commercial loans | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		44	205
One year prior to current year		143	0
Two years prior to current year		12	38
Three years prior to current year		108	213
Four years prior to current year		112	61
Prior		213	143
Revolving Loans		361	427
Revolving Loans Converted to Term Loans		11	3
Total		1,004	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		40	0
Two years prior to current year		0	22
Three years prior to current year		104	212
Four years prior to current year		92	27
Prior		42	19
Revolving Loans		3	63
Revolving Loans Converted to Term Loans		3	3
Total		284	550
Commercial loans | Special mention | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		38	1
One year prior to current year		103	0
Two years prior to current year		12	16
Three years prior to current year		4	1
Four years prior to current year		20	34
Prior		126	116
Revolving Loans		296	182
Revolving Loans Converted to Term Loans		8	0
Total		607	350
Commercial loans | Special mention | 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		45	8
Revolving Loans		62	182
Revolving Loans Converted to Term Loans		0	0
Total		107	190
Commercial loans | Special mention | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		6
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		0
Revolving Loans		0
Revolving Loans Converted to Term Loans		0
Total		6
Commercial loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		71	236
One year prior to current year		36	43
Two years prior to current year		0	74
Three years prior to current year		28	81
Four years prior to current year		0	687
Prior		1,091	1,031
Revolving Loans		819	760
Revolving Loans Converted to Term Loans		1	1
Total		2,046	2,913
Commercial loans | Substandard | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		2	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		0	677
Prior		821	891
Revolving Loans		0	19
Revolving Loans Converted to Term Loans		0	0
Total		824	1,700
Commercial loans | Substandard | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		31	3
One year prior to current year		22	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		156	138
Revolving Loans		746	548
Revolving Loans Converted to Term Loans		1	1
Total		983	770
Commercial loans | Substandard | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	232
One year prior to current year		14	0
Two years prior to current year		0	0
Three years prior to current year		0	16
Four years prior to current year		0	0
Prior		114	2
Revolving Loans		73	186
Revolving Loans Converted to Term Loans		0	0
Total		201	436
Commercial loans | Substandard | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		38	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	0
Revolving Loans		0	7
Revolving Loans Converted to Term Loans		0	0
Total		38	7
Commercial loans | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	31
One year prior to current year		187	0
Two years prior to current year		36	9
Three years prior to current year		0	0
Four years prior to current year		14	15
Prior		175	0
Revolving Loans		93	46
Revolving Loans Converted to Term Loans		0	4
Total		505	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		166
Revolving Loans		18
Revolving Loans Converted to Term Loans		0
Total		184
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		36	9
Three years prior to current year		0	0
Four years prior to current year		0	15
Prior		9	0
Revolving Loans		71	24
Revolving Loans Converted to Term Loans		0	4
Total		116	52
Commercial loans | Doubtful | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	0
One year prior to current year		187	0
Two years prior to current year		0	0
Three years prior to current year		0	0
Four years prior to current year		14	0
Prior		0	0
Revolving Loans		1	15
Revolving Loans Converted to Term Loans		0	0
Total		202	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		0	0
Revolving Loans		3	7
Revolving Loans Converted to Term Loans		0	0
Total		$ 3	$ 38

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at December 31, 2023 and 2022. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 27, "Variable Interest Entities," for additional information. At December 31,20232022(in millions)AssetsLoans, net$— $162 Other assets23 44 Total assets$23 $206 LiabilitiesInterest, taxes and other liabilities$17 $22 Total liabilities$17 $22