Loans - Summary of Past Due Status of Loans (Detail) - USD ($) $ in Millions		Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Loans, net	[1]	$ 57,945	$ 59,380
Commercial loans
Financing Receivable, Past Due [Line Items]
Loans, net		39,811	41,817
Commercial loans | Real estate, including construction
Financing Receivable, Past Due [Line Items]
Loans, net		7,185	7,963
Commercial loans | Business and corporate banking
Financing Receivable, Past Due [Line Items]
Loans, net		16,169	16,075
Commercial loans | Global banking
Financing Receivable, Past Due [Line Items]
Loans, net		10,127	10,578
Commercial loans | Other commercial
Financing Receivable, Past Due [Line Items]
Loans, net		6,330	7,201
Consumer loans
Financing Receivable, Past Due [Line Items]
Loans, net		18,134	17,563
Consumer loans | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		17,452	16,838
Consumer loans | Home equity mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		364	370
Consumer loans | Credit cards
Financing Receivable, Past Due [Line Items]
Loans, net		197	213
Consumer loans | Other consumer
Financing Receivable, Past Due [Line Items]
Loans, net		121	142
Past Due
Financing Receivable, Past Due [Line Items]
Loans, net		917	833
Past Due | Commercial loans
Financing Receivable, Past Due [Line Items]
Loans, net		654	536
Past Due | Commercial loans | Real estate, including construction
Financing Receivable, Past Due [Line Items]
Loans, net		274	28
Past Due | Commercial loans | Business and corporate banking
Financing Receivable, Past Due [Line Items]
Loans, net		113	36
Past Due | Commercial loans | Global banking
Financing Receivable, Past Due [Line Items]
Loans, net		58	8
Past Due | Commercial loans | Other commercial
Financing Receivable, Past Due [Line Items]
Loans, net		209	464
Past Due | Consumer loans
Financing Receivable, Past Due [Line Items]
Loans, net		263	297
Past Due | Consumer loans | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		248	285
Past Due | Consumer loans | Home equity mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		4	5
Past Due | Consumer loans | Credit cards
Financing Receivable, Past Due [Line Items]
Loans, net		5	4
Past Due | Consumer loans | Other consumer
Financing Receivable, Past Due [Line Items]
Loans, net		6	3
30 - 89 Days
Financing Receivable, Past Due [Line Items]
Loans, net		665	690
30 - 89 Days | Commercial loans
Financing Receivable, Past Due [Line Items]
Loans, net		498	504
30 - 89 Days | Commercial loans | Real estate, including construction
Financing Receivable, Past Due [Line Items]
Loans, net		168	27
30 - 89 Days | Commercial loans | Business and corporate banking
Financing Receivable, Past Due [Line Items]
Loans, net		110	13
30 - 89 Days | Commercial loans | Global banking
Financing Receivable, Past Due [Line Items]
Loans, net		11	0
30 - 89 Days | Commercial loans | Other commercial
Financing Receivable, Past Due [Line Items]
Loans, net		209	464
30 - 89 Days | Consumer loans
Financing Receivable, Past Due [Line Items]
Loans, net		167	186
30 - 89 Days | Consumer loans | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		160	180
30 - 89 Days | Consumer loans | Home equity mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		1	2
30 - 89 Days | Consumer loans | Credit cards
Financing Receivable, Past Due [Line Items]
Loans, net		2	2
30 - 89 Days | Consumer loans | Other consumer
Financing Receivable, Past Due [Line Items]
Loans, net		4	2
90+ Days
Financing Receivable, Past Due [Line Items]
Loans, net		252	143
90+ Days | Commercial loans
Financing Receivable, Past Due [Line Items]
Loans, net		156	32
90+ Days | Commercial loans | Real estate, including construction
Financing Receivable, Past Due [Line Items]
Loans, net		106	1
90+ Days | Commercial loans | Business and corporate banking
Financing Receivable, Past Due [Line Items]
Loans, net		3	23
90+ Days | Commercial loans | Global banking
Financing Receivable, Past Due [Line Items]
Loans, net		47	8
90+ Days | Commercial loans | Other commercial
Financing Receivable, Past Due [Line Items]
Loans, net		0	0
90+ Days | Consumer loans
Financing Receivable, Past Due [Line Items]
Loans, net		96	111
90+ Days | Consumer loans | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		88	105
90+ Days | Consumer loans | Home equity mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		3	3
90+ Days | Consumer loans | Credit cards
Financing Receivable, Past Due [Line Items]
Loans, net		3	2
90+ Days | Consumer loans | Other consumer
Financing Receivable, Past Due [Line Items]
Loans, net		2	1
Current
Financing Receivable, Past Due [Line Items]
Loans, net		57,028	58,547
Current | Commercial loans
Financing Receivable, Past Due [Line Items]
Loans, net		39,157	41,281
Current | Commercial loans | Real estate, including construction
Financing Receivable, Past Due [Line Items]
Loans, net		6,911	7,935
Current | Commercial loans | Business and corporate banking
Financing Receivable, Past Due [Line Items]
Loans, net		16,056	16,039
Current | Commercial loans | Global banking
Financing Receivable, Past Due [Line Items]
Loans, net		10,069	10,570
Current | Commercial loans | Other commercial
Financing Receivable, Past Due [Line Items]
Loans, net		6,121	6,737
Current | Consumer loans
Financing Receivable, Past Due [Line Items]
Loans, net		17,871	17,266
Current | Consumer loans | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		17,204	16,553
Current | Consumer loans | Home equity mortgages
Financing Receivable, Past Due [Line Items]
Loans, net		360	365
Current | Consumer loans | Credit cards
Financing Receivable, Past Due [Line Items]
Loans, net		192	209
Current | Consumer loans | Other consumer
Financing Receivable, Past Due [Line Items]
Loans, net		$ 115	$ 139

[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