Loans - Delinquency Ratio for Consumer Loan (Detail) - Consumer Loans [Member] - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans		$ 416	$ 405
Delinquency Ratio		2.04%	2.05%
Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans	[1],[2]	$ 350	$ 347
Delinquency Ratio	[1],[2]	1.96%	1.99%
Home Equity Mortgages [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans	[1],[2]	$ 25	$ 30
Delinquency Ratio	[1],[2]	2.93%	3.05%
Credit Cards [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans		$ 34	$ 20
Delinquency Ratio		2.42%	1.96%
Other consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Delinquent Loans		$ 7	$ 8
Delinquency Ratio		2.47%	2.62%

[1] At December 31, 2019 and 2018, consumer mortgage loan delinquency includes $256 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.

[2] At December 31, 2019 and 2018, consumer mortgage loans include $142 million and $125 million, respectively, of loans that were in the process of foreclosure.