Loans - Status of Consumer Loan Portfolio (Detail) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Accruing Loans Contractually Past Due 90 days or More		$ 23	$ 21
Total loans		72,478	68,978	$ 66,399
Consumer Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		19,293	19,220
Nonaccrual Loans		418	396
Accruing Loans Contractually Past Due 90 days or More		22	20
Total loans		19,733	19,636
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		17,051	17,042
Nonaccrual Loans	[1],[2],[3]	370	341
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		17,421	17,383	17,326
Consumer Loans [Member] | Home Equity Mortgages [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		863	927
Nonaccrual Loans	[1],[3]	48	55
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		911	982	1,086
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		1,111	1,005
Nonaccrual Loans		0	0
Accruing Loans Contractually Past Due 90 days or More		18	14
Total loans		1,129	1,019	841
Consumer Loans [Member] | Other consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		268	246
Nonaccrual Loans		0	0
Accruing Loans Contractually Past Due 90 days or More		4	6
Total loans		$ 272	$ 252	$ 303

[1] At June 30, 2019 and December 31, 2018, nonaccrual consumer mortgage loans held for investment include $267 million and $289 million, respectively, of loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell.

[2] Nonaccrual consumer mortgage loans for all periods does not include guaranteed loans purchased from the Government National Mortgage Association. Repayment of these loans is predominantly insured by the Federal Housing Administration and as such, these loans have different risk characteristics from the rest of our consumer loan portfolio.

[3] Nonaccrual consumer mortgage loans held for investment include all loans which are 90 or more days contractually delinquent as well as loans discharged under Chapter 7 bankruptcy and not re-affirmed and second lien loans where the first lien loan that we own or service is 90 or more days contractually delinquent.