Loans - Summary of Loans and Lending Commitments Accounted for at Amortized Cost by Portfolio (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 162,135	$ 119,989
Lending commitments	197,120	162,513
Corporate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	55,927	48,659
Wealth management [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	43,998	33,023
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	25,883	20,290
Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	15,913	5,750
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,530	4,174
Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,672	3,823
Credit card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,212	4,270
Wholesale Portfolio Segment [Member] \| Corporate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	50,960	44,778
Lending commitments	143,296	127,756
Wholesale Portfolio Segment [Member] \| Wealth management [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	38,062	25,151
Lending commitments	4,091	2,314
Wholesale Portfolio Segment [Member] \| Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	21,150	17,096
Lending commitments	4,306	4,154
Wholesale Portfolio Segment [Member] \| Residential real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	15,493	5,236
Lending commitments	3,317	1,804
Wholesale Portfolio Segment [Member] \| Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	5,958	3,211
Lending commitments	6,169	4,841
Consumer Portfolio Segment [Member] \| Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	3,672	3,823
Lending commitments	9	4
Consumer Portfolio Segment [Member] \| Credit card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	8,212	4,270
Lending commitments	35,932	21,640
Wholesale and Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	143,507	103,565
Lending commitments	$ 197,120	$ 162,513