Loans - Status of Consumer Loan Portfolio (Detail) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Accruing Loans Contractually Past Due 90 days or More		$ 25	$ 21
Total loans		71,336	68,978	$ 66,756
Consumer Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		19,577	19,220
Nonaccrual Loans		418	396
Accruing Loans Contractually Past Due 90 days or More		24	20
Total loans		20,019	19,636
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		17,203	17,042
Nonaccrual Loans	[1],[2],[3]	371	341
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		17,574	17,383	17,376
Consumer Loans [Member] | Home Equity Mortgages [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		833	927
Nonaccrual Loans	[1],[3]	47	55
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		880	982	1,027
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		1,290	1,005
Nonaccrual Loans		0	0
Accruing Loans Contractually Past Due 90 days or More		18	14
Total loans		1,308	1,019	907
Consumer Loans [Member] | Other consumer [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Performing Loans		251	246
Nonaccrual Loans		0	0
Accruing Loans Contractually Past Due 90 days or More		6	6
Total loans		$ 257	$ 252	$ 263

[1] At September 30, 2019 and December 31, 2018, nonaccrual consumer mortgage loans held for investment include $273 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.