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Allowance for Loan Losses - Average Recorded Investment and Interest Income Recognized for TDR (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Receivables [Abstract]        
Impaired financing receivable, Average recorded investment $ 9,995 $ 10,733 $ 10,025 $ 10,794
Impaired financing receivable, Interest income recognized $ 194 $ 187 $ 392 $ 367