v3.21.2
Credit Concentrations - Credit Concentration, Government and Federal Agency Obligations (Detail) - USD ($)
$ in Millions
9 Months Ended 12 Months Ended
Sep. 30, 2021
Dec. 31, 2020
U.S. Government and Agency Obligations Held By The Firm [Member]    
Concentration Risk [Line Items]    
Concentration risk, Credit risk, Financial instrument, Maximum exposure $ 147,262 $ 187,009
Concentration risk, Credit risk, Financial instrument, Maximum exposure, As a percentage of total Assets 10.20% 16.10%
Non-U.S. Government and Agency Obligations Held By The Firm [Member]    
Concentration Risk [Line Items]    
Concentration risk, Credit risk, Financial instrument, Maximum exposure $ 58,520 $ 59,580
Concentration risk, Credit risk, Financial instrument, Maximum exposure, As a percentage of total Assets 4.10% 5.10%