Loans - Summary of Receivables which were Modified and as Result Became Classified as TDR Loans (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	$ 107	$ 118
Commercial loans
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	99	101
Commercial loans | Business and corporate banking
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	99	101
Consumer loans
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	8	17
Consumer loans | Residential mortgages
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	5	12
Consumer loans | Home equity mortgages
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	2	2
Consumer loans | Credit cards
Financing Receivable, Impaired [Line Items]
Loans which were modified and as a result became classified as TDR Loans	$ 1	$ 3