Loans - Status of Consumer Loan Portfolio (Detail) - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Accruing Loans Contractually Past Due 90 days or More		$ 21	$ 21
Total loans		71,034	68,978	$ 67,338
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		19,213	19,220
Nonaccrual Loans		394	396
Accruing Loans Contractually Past Due 90 days or More		20	20
Total loans		19,627	19,636
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		17,024	17,042
Nonaccrual Loans	[1],[2],[3]	344	341
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		17,368	17,383	17,325
Consumer Loans [Member] | Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		891	927
Nonaccrual Loans	[1],[3]	50	55
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		941	982	1,139
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		1,025	1,005
Nonaccrual Loans		0	0
Accruing Loans Contractually Past Due 90 days or More		15	14
Total loans		1,040	1,019	770
Consumer Loans [Member] | Other consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		273	246
Nonaccrual Loans		0	0
Accruing Loans Contractually Past Due 90 days or More		5	6
Total loans		$ 278	$ 252	$ 365

[1] At March 31, 2019 and December 31, 2018, nonaccrual consumer mortgage loans held for investment include $262 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.