v3.21.2
Securitization Activities - Firms Continuing Involvement in Securitization Entities to Which Firm Sold Assets (Detail) - USD ($)
$ in Millions
Sep. 30, 2021
Dec. 31, 2020
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]    
Outstanding principal amount $ 108,266 $ 87,742
Retained interests 3,623 3,182
Purchased interests 167 66
U.S. government agency-issued CMOs [Member]    
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]    
Outstanding principal amount 30,081 20,841
Retained interests 1,149 906
Purchased interests 1 4
Other Residential Mortgage-backed [Member]    
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]    
Outstanding principal amount 23,252 24,262
Retained interests 1,039 1,170
Purchased interests 36 23
Other Commercial Mortgage-backed [Member]    
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]    
Outstanding principal amount 47,283 38,340
Retained interests 1,083 914
Purchased interests 88 39
Corporate debt and other asset-backed [Member]    
Qualitative and Quantitative Information, Transferor's Continuing Involvement [Line Items]    
Outstanding principal amount 7,650 4,299
Retained interests 352 192
Purchased interests $ 42 $ 0