v3.21.2
Loans - Fair value of loans held for investment by level (Detail) - USD ($)
$ in Millions
Sep. 30, 2021
Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans $ 12,104 $ 13,625
Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 9,905 10,947
Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 2,199 2,678
Corporate [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 3,020 2,751
Corporate [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 2,245 1,822
Corporate [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 775 929
Wealth management [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 6,616 7,872
Wealth management [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 6,553 7,809
Wealth management [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 63 63
Commercial real estate [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 1,655 1,961
Commercial real estate [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 719 857
Commercial real estate [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 936 1,104
Residential real estate [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 351 494
Residential real estate [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 185 234
Residential real estate [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 166 260
Other [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 462 547
Other [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 203 225
Other [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans $ 259 $ 322