v3.20.4
Fair Value Measurements - Total Level 3 Financial Assets (Detail) - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total financial assets at fair value $ 627,073 $ 539,568
Investment at fair value 82,778 57,827
Loans receivable at fair value 13,625 14,386
Derivatives [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total financial assets at fair value 146,751 100,779
Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total financial assets at fair value 26,305 23,068
Loans receivable at fair value 2,678 1,890
Level 3 [Member] | Trading cash instruments [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Trading cash instrument at fair value 1,237 1,242
Level 3 [Member] | Derivatives [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total financial assets at fair value 5,967 4,654
Level 3 [Member] | Investments [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Investment at fair value 16,423 15,282
Level 3 [Member] | Loans [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Loans receivable at fair value $ 2,678 $ 1,890