Loans - Status of Consumer Loan Portfolio (Detail) - USD ($) $ in Millions		Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Accruing Loans Contractually Past Due 90 days or More		$ 17	$ 18
Total loans		69,588	73,875	$ 81,732
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		19,059	19,132
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest		517	510
Accruing Loans Contractually Past Due 90 days or More		16	17
Total loans		19,592	19,659
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		16,773	16,746
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest	[1],[2],[3]	446	435
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		17,219	17,181	17,521
Consumer Loans [Member] | Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		1,273	1,333
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest	[1],[3]	71	75
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		1,344	1,408	1,544
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		637	678
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest		0	0
Accruing Loans Contractually Past Due 90 days or More		9	10
Total loans		646	688	660
Consumer Loans [Member] | Other consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		376	375
Loans and Leases Receivable, Nonperforming, Nonaccrual of Interest		0	0
Accruing Loans Contractually Past Due 90 days or More		7	7
Total loans		$ 383	$ 382	$ 395

[1] At March 31, 2017 and December 31, 2016, nonaccrual consumer mortgage loans held for investment include $396 million and $382 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 are 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.