Loans - Delinquency Ratio for Consumer Loan (Detail) - Consumer Loans [Member] - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans		$ 411	$ 486
Delinquency Ratio		2.09%	2.48%
Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	[1],[2]	$ 356	$ 425
Delinquency Ratio	[1],[2]	2.05%	2.46%
Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	[1],[2]	$ 32	$ 39
Delinquency Ratio	[1],[2]	2.95%	3.27%
Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans		$ 15	$ 12
Delinquency Ratio		1.78%	1.66%
Other consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans		$ 8	$ 10
Delinquency Ratio		2.23%	2.48%

[1] At June 30, 2018 and December 31, 2017, consumer mortgage loan delinquency includes $285 million and $342 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 June 30, 2018 and December 31, 2017, consumer mortgage loans and loans held for sale include $162 million and $159 million, respectively, of loans that were in the process of foreclosure.