Loans - Consumer, Excluding Credit Card Loans, Financial Effects of Modifications and Redefaults (Details) - Consumer, excluding credit card $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) loan_payment	Jun. 30, 2014 USD ($)
Residential mortgage
Financing Receivable, Impaired [Line Items]
Number of payments past due for deemed payment | loan_payment			2
Permanent Modification | Home equity - senior lien
Financing Receivable, Impaired [Line Items]
Weighted-average interest rate of loans with interest rate reductions – before TDR	5.88%	6.58%	5.98%	6.63%
Weighted-average interest rate of loans with interest rate reductions – after TDR	2.89%	2.93%	2.81%	2.98%
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – before TDR	17 years	17 years	17 years	18 years
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – after TDR	31 years	29 years	31 years	30 years
Charge-offs recognized upon permanent modification	$ 0	$ 0	$ 0	$ 1
Principal deferred	4	1	7	2
Principal forgiven	1	3	2	6
Balance of loans that redefaulted within one year of permanent modification(a)	$ 4	$ 4	$ 6	$ 10
Modifications, weighted-average remaining life			6 years
Permanent Modification | Home equity - junior lien
Financing Receivable, Impaired [Line Items]
Weighted-average interest rate of loans with interest rate reductions – before TDR	4.65%	4.94%	4.79%	4.83%
Weighted-average interest rate of loans with interest rate reductions – after TDR	2.23%	2.04%	2.22%	1.91%
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – before TDR	19 years	19 years	19 years	19 years
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – after TDR	33 years	34 years	34 years	35 years
Charge-offs recognized upon permanent modification	$ 1	$ 8	$ 2	$ 22
Principal deferred	3	3	6	6
Principal forgiven	0	6	0	17
Balance of loans that redefaulted within one year of permanent modification(a)	$ 1	$ 3	$ 3	$ 6
Modifications, weighted-average remaining life			8 years
Permanent Modification | Mortgages - prime, including option ARMS
Financing Receivable, Impaired [Line Items]
Weighted-average interest rate of loans with interest rate reductions – before TDR	5.15%	5.17%	5.09%	5.20%
Weighted-average interest rate of loans with interest rate reductions – after TDR	2.50%	2.54%	2.44%	2.67%
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – before TDR	25 years	25 years	25 years	24 years
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – after TDR	38 years	37 years	38 years	37 years
Charge-offs recognized upon permanent modification	$ 2	$ 2	$ 3	$ 4
Principal deferred	11	10	22	23
Principal forgiven	7	8	16	25
Balance of loans that redefaulted within one year of permanent modification(a)	$ 21	$ 44	$ 37	$ 70
Modifications, weighted-average remaining life			9 years
Permanent Modification | Mortgages - subprime
Financing Receivable, Impaired [Line Items]
Weighted-average interest rate of loans with interest rate reductions – before TDR	6.55%	7.28%	6.69%	7.44%
Weighted-average interest rate of loans with interest rate reductions – after TDR	3.16%	3.47%	3.19%	3.43%
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – before TDR	24 years	24 years	24 years	24 years
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – after TDR	36 years	35 years	36 years	36 years
Charge-offs recognized upon permanent modification	$ 1	$ 0	$ 2	$ 1
Principal deferred	3	4	10	11
Principal forgiven	7	11	17	32
Balance of loans that redefaulted within one year of permanent modification(a)	$ 16	$ 28	$ 31	$ 43
Modifications, weighted-average remaining life			8 years
Permanent Modification | Residential real estate – excluding PCI
Financing Receivable, Impaired [Line Items]
Weighted-average interest rate of loans with interest rate reductions – before TDR	5.48%	5.82%	5.58%	5.88%
Weighted-average interest rate of loans with interest rate reductions – after TDR	2.65%	2.72%	2.65%	2.75%
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – before TDR	22 years	23 years	23 years	23 years
Weighted-average remaining contractual term (in years) of loans with term or payment extensions – after TDR	35 years	35 years	36 years	36 years
Charge-offs recognized upon permanent modification	$ 4	$ 10	$ 7	$ 28
Principal deferred	21	18	45	42
Principal forgiven	15	28	35	80
Balance of loans that redefaulted within one year of permanent modification(a)	$ 42	$ 79	$ 77	$ 129
Maximum | Residential real estate – excluding PCI
Financing Receivable, Impaired [Line Items]
Number of months before a payment redefault under modified loans			12 months
Maximum | Business banking
Financing Receivable, Impaired [Line Items]
Number of years before payment default under a modified loan			1 year