Loans - Status of Consumer Loan Portfolio (Detail) - USD ($) $ in Millions		Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Accruing Loans Contractually Past Due 90 days or More		$ 21		$ 18
Total loans		68,978		72,563	$ 73,875
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		19,220		19,030
Nonaccrual Loans		396		481
Accruing Loans Contractually Past Due 90 days or More		20		17
Total loans		19,636		19,528
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		17,042		16,859
Nonaccrual Loans	[1],[2],[3]	341		414
Accruing Loans Contractually Past Due 90 days or More		0		0
Total loans		17,383		17,273	17,181
Consumer Loans [Member] | Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		927		1,124
Nonaccrual Loans	[1],[3]	55		67
Accruing Loans Contractually Past Due 90 days or More		0		0
Total loans		982	[4]	1,191	1,408
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		1,005		712
Nonaccrual Loans		0		0
Accruing Loans Contractually Past Due 90 days or More		14		9
Total loans		1,019	[5]	721	688
Consumer Loans [Member] | Other consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		246		335
Nonaccrual Loans		0		0
Accruing Loans Contractually Past Due 90 days or More		6		8
Total loans		$ 252		$ 343	$ 382

[1] At December 31, 2018 and 2017, nonaccrual consumer mortgage loans held for investment include $289 million and $360 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.

[4] Home equity mortgage maturities reflect estimates based on historical payment patterns.

[5] As credit card receivables do not have stated maturities, the table reflects estimates based on historical payment patterns.