XML 93 R76.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Allowance for Credit Losses - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Minimum delinquency period for loan level collectability analysis consumer mortgage 150 days  
Residential Mortgage Loans [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Carrying value of loans for which partial charge-off has been recognized $ 25 $ 29
Mortgage loans on real real estate not requiring charge off due to collateral carrying amount 18 21
Home Equity Loans and Lines of Credit [Member]    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Carrying value of loans for which partial charge-off has been recognized 19 23
Mortgage loans on real real estate not requiring charge off due to collateral carrying amount $ 29 $ 31