Fair Value Measurements - Summary of Level 3 Financial Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	$ 758,400	$ 722,276	$ 650,966
Investments at fair value	76,307		78,201
Loans at fair value	6,448		7,655
Other assets at fair value	324		145
Derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	108,461		117,268
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	24,862	25,945	26,048
Loans at fair value	972		1,837
Other assets at fair value	151		74
Level 3 | Trading cash instruments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading cash instrument at fair value	1,753	1,664	1,734
Level 3 | Derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets at fair value	4,657	4,776	5,461
Level 3 | Investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments at fair value	17,329	18,128	16,942
Level 3 | Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans at fair value	972	1,251	1,837
Level 3 | Other assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets at fair value	$ 151	$ 126	$ 74