Loans - Delinquency Ratio for Consumer Loan (Detail) - Consumer Loans [Member] - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans		$ 391	$ 405
Delinquency Ratio		1.95%	2.05%
Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans	[1],[2]	$ 332	$ 347
Delinquency Ratio	[1],[2]	1.88%	1.99%
Home Equity Mortgages [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans	[1],[2]	$ 26	$ 30
Delinquency Ratio	[1],[2]	2.95%	3.05%
Credit Cards [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans		$ 26	$ 20
Delinquency Ratio		1.99%	1.96%
Other consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans		$ 7	$ 8
Delinquency Ratio		2.72%	2.62%

[1] At September 30, 2019 and December 31, 2018, consumer mortgage loan delinquency includes $240 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 September 30, 2019 and December 31, 2018, consumer mortgage loans and loans held for sale include $140 million and $125 million, respectively, of loans that were in the process of foreclosure.