Loans - Summary of TDRs (Detail) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR Loans	$ 267	$ 200
Residential mortgage loan TDR carried at lower of amortized cost or fair value less cost to sell	102	104
Non Accrual loans included in TDR loan	67	115
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR Loans	115	63
Additional commitments to lend to commercial borrowers with modified TDRs	13	13
Commercial loans | Business and corporate banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR Loans	112	38
Commercial loans | Global banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR Loans	3	25
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR Loans	152	137
Transfer TDR loans held-for-sale to portfolio loans	24
Consumer loans | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR Loans	137	125
Consumer loans | Home equity mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR Loans	13	9
Consumer loans | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR Loans	$ 2	$ 3