Loans - Credit Risk Profile of 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 | Investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		3,217	2,652
One year prior to current year		1,705	1,055
Two years prior to current year		1,261	1,157
Three years prior to current year		807	849
Four years prior to current year		1,028	1,012
Prior		6,322	6,882
Revolving Loans		8,595	10,773
Revolving Loans Converted to Term Loans		54	21
Total		22,989	24,401
Commercial loans | Investment grade | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		327	80
One year prior to current year		100	45
Two years prior to current year		24	305
Three years prior to current year		187	178
Four years prior to current year		162	783
Prior		939	278
Revolving Loans		1	0
Revolving Loans Converted to Term Loans		0	0
Total		1,740	1,669
Commercial loans | Investment grade | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		732	491
One year prior to current year		304	484
Two years prior to current year		543	122
Three years prior to current year		95	444
Four years prior to current year		261	71
Prior		1,977	2,758
Revolving Loans		3,311	3,657
Revolving Loans Converted to Term Loans		54	21
Total		7,277	8,048
Commercial loans | Investment grade | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		1,947	1,814
One year prior to current year		1,109	449
Two years prior to current year		651	212
Three years prior to current year		149	146
Four years prior to current year		307	84
Prior		2,842	2,911
Revolving Loans		2,140	3,006
Revolving Loans Converted to Term Loans		0	0
Total		9,145	8,622
Commercial loans | Investment grade | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		211	267
One year prior to current year		192	77
Two years prior to current year		43	518
Three years prior to current year		376	81
Four years prior to current year		298	74
Prior		564	935
Revolving Loans		3,143	4,110
Revolving Loans Converted to Term Loans		0	0
Total		4,827	6,062
Commercial loans | Non-investment grade
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		1,439	2,096
One year prior to current year		2,163	1,430
Two years prior to current year		1,989	657
Three years prior to current year		581	2,260
Four years prior to current year		1,326	1,299
Prior		4,747	5,115
Revolving Loans		4,459	4,370
Revolving Loans Converted to Term Loans		264	189
Total		16,968	17,416
Commercial loans | Non-investment grade | Real estate, including construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		593	1,235
One year prior to current year		1,186	809
Two years prior to current year		995	215
Three years prior to current year		168	1,536
Four years prior to current year		892	1,020
Prior		1,470	1,434
Revolving Loans		40	42
Revolving Loans Converted to Term Loans		3	3
Total		5,347	6,294
Commercial loans | Non-investment grade | Business and corporate banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		538	625
One year prior to current year		844	344
Two years prior to current year		531	353
Three years prior to current year		136	371
Four years prior to current year		300	237
Prior		2,276	2,261
Revolving Loans		3,611	3,650
Revolving Loans Converted to Term Loans		211	186
Total		8,447	8,027
Commercial loans | Non-investment grade | Global banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		308	220
One year prior to current year		44	0
Two years prior to current year		193	0
Three years prior to current year		2	31
Four years prior to current year		14	30
Prior		758	1,241
Revolving Loans		211	434
Revolving Loans Converted to Term Loans		50	0
Total		1,580	1,956
Commercial loans | Non-investment grade | Other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Current year		0	16
One year prior to current year		89	277
Two years prior to current year		270	89
Three years prior to current year		275	322
Four years prior to current year		120	12
Prior		243	179
Revolving Loans		597	244
Revolving Loans Converted to Term Loans		0	0
Total		$ 1,594	$ 1,139

[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