Loans - Delinquency Ratio for Consumer Loan (Detail) - Consumer Loans [Member] - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans		$ 414	$ 405
Delinquency Ratio		2.11%	2.05%
Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	[1],[2]	$ 356	$ 347
Delinquency Ratio	[1],[2]	2.05%	1.99%
Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	[1],[2]	$ 29	$ 30
Delinquency Ratio	[1],[2]	3.08%	3.05%
Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans		$ 22	$ 20
Delinquency Ratio		2.12%	1.96%
Other consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans		$ 7	$ 8
Delinquency Ratio		2.52%	2.62%

[1] At March 31, 2019 and December 31, 2018, consumer mortgage loan delinquency includes $223 million and $254 million, respectively, of loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell, including $1 million and $1 million, respectively, relating to loans held for sale.

[2] At March 31, 2019 and December 31, 2018, consumer mortgage loans and loans held for sale include $135 million and $125 million, respectively, of loans that were in the process of foreclosure.