v3.20.4
Loans - Summary of Credit Concentration by Region (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Product Information [Line Items]    
Loans and Leases Receivable, Gross $ 119,989 $ 110,345
Concentration Risk,Percentage 100.00% 100.00%
Americas [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 75.00% 73.00%
Europe, Middle East and Africa [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 19.00% 21.00%
Asia [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 6.00% 6.00%
Corporate [Member]    
Product Information [Line Items]    
Loans and Leases Receivable, Gross $ 48,659 $ 46,307
Concentration Risk,Percentage 100.00% 100.00%
Corporate [Member] | Americas [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 60.00% 60.00%
Corporate [Member] | Europe, Middle East and Africa [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 31.00% 31.00%
Corporate [Member] | Asia [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 9.00% 9.00%
Wealth management [Member]    
Product Information [Line Items]    
Loans and Leases Receivable, Gross $ 33,023 $ 27,940
Concentration Risk,Percentage 100.00% 100.00%
Wealth management [Member] | Americas [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 88.00% 88.00%
Wealth management [Member] | Europe, Middle East and Africa [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 10.00% 9.00%
Wealth management [Member] | Asia [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 2.00% 3.00%
Commercial real estate [Member]    
Product Information [Line Items]    
Loans and Leases Receivable, Gross $ 20,290 $ 17,743
Concentration Risk,Percentage 100.00% 100.00%
Commercial real estate [Member] | Americas [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 71.00% 69.00%
Commercial real estate [Member] | Europe, Middle East and Africa [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 19.00% 21.00%
Commercial real estate [Member] | Asia [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 10.00% 10.00%
Residential real estate [Member]    
Product Information [Line Items]    
Loans and Leases Receivable, Gross $ 5,750 $ 6,958
Concentration Risk,Percentage 100.00% 100.00%
Residential real estate [Member] | Americas [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 88.00% 90.00%
Residential real estate [Member] | Europe, Middle East and Africa [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 9.00% 9.00%
Residential real estate [Member] | Asia [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 3.00% 1.00%
Installment [Member]    
Product Information [Line Items]    
Loans and Leases Receivable, Gross $ 3,823 $ 4,747
Concentration Risk,Percentage 100.00% 100.00%
Installment [Member] | Americas [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 100.00% 100.00%
Credit card [Member]    
Product Information [Line Items]    
Loans and Leases Receivable, Gross $ 4,270 $ 1,858
Concentration Risk,Percentage 100.00% 100.00%
Credit card [Member] | Americas [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 100.00% 100.00%
Other [Member]    
Product Information [Line Items]    
Loans and Leases Receivable, Gross $ 4,174 $ 4,792
Concentration Risk,Percentage 100.00% 100.00%
Other [Member] | Americas [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 81.00% 87.00%
Other [Member] | Europe, Middle East and Africa [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 17.00% 12.00%
Other [Member] | Asia [Member]    
Product Information [Line Items]    
Concentration Risk,Percentage 2.00% 1.00%