v3.20.4
Loans - Fair value of loans held for investment by level (Detail) - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans $ 13,625 $ 14,386
Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 10,947 12,496
Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 2,678 1,890
Corporate [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 2,751 3,224
Corporate [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 1,822 2,472
Corporate [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 929 752
Wealth management [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 7,872 7,824
Wealth management [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 7,809 7,764
Wealth management [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 63 60
Commercial real estate [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 1,961 1,876
Commercial real estate [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 857 1,285
Commercial real estate [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 1,104 591
Residential real estate [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 494 792
Residential real estate [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 234 571
Residential real estate [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 260 221
Other [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 547 670
Other [Member] | Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans 225 404
Other [Member] | Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans $ 322 $ 266