Loans - Summary of Receivables which were Modified and as Result Became Classified as TDR Loans (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	$ 5	$ 1	$ 123	$ 76
Commercial loans
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	0	0	101	41
Commercial loans | Business and corporate banking
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	0	0	101	26
Commercial loans | Global banking
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	0	0	0	15
Consumer loans
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	5	1	22	35
Consumer loans | Residential mortgages
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	5	1	17	33
Consumer loans | Home equity mortgages
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	0	0	2	1
Consumer loans | Credit cards
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	$ 0	$ 0	$ 3	$ 1