Loans - Summary of Estimated Fair Value of Loans and Lending Commitments that are not Accounted for at Fair Value (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Schedule Of Estimated Fair Value Of Loans And Lending Commitments That Are Not Accounted For At Fair Value [Line Items]
Loans	$ 176,669	$ 158,562
Amortized Cost
Schedule Of Estimated Fair Value Of Loans And Lending Commitments That Are Not Accounted For At Fair Value [Line Items]
Loans	161,619	139,934
Loans, Estimated Fair Value, Level 3	163,232	141,803
Amortized Cost | Level 2
Schedule Of Estimated Fair Value Of Loans And Lending Commitments That Are Not Accounted For At Fair Value [Line Items]
Loans, Estimated Fair Value, Level 1	85,846	87,676
Amortized Cost | Level 3
Schedule Of Estimated Fair Value Of Loans And Lending Commitments That Are Not Accounted For At Fair Value [Line Items]
Loans, Estimated Fair Value, Level 2	77,386	54,127
Held For Sale
Schedule Of Estimated Fair Value Of Loans And Lending Commitments That Are Not Accounted For At Fair Value [Line Items]
Loans	6,800	7,859
Loans held for sale	6,800	7,859
Loans held for sale, Estimated Fair Value, Level 3	6,810	7,887
Held For Sale | Level 2
Schedule Of Estimated Fair Value Of Loans And Lending Commitments That Are Not Accounted For At Fair Value [Line Items]
Loans held for sale, Estimated Fair Value, Level 1	3,589	5,970
Held For Sale | Level 3
Schedule Of Estimated Fair Value Of Loans And Lending Commitments That Are Not Accounted For At Fair Value [Line Items]
Loans held for sale, Estimated Fair Value, Level 2	$ 3,221	$ 1,917