Asset Quality (Financial Impact and TDRs by Concession Type) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) loans	Jun. 30, 2014 USD ($) loans	Jun. 30, 2015 USD ($) loans	Jun. 30, 2014 USD ($) loans
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	2,806	2,713	5,461	5,836
Pre-TDR Recorded Investment	$ 128	$ 168	$ 260	$ 339
Post-TDR Recorded Investment	111	160	230	310
Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	4	3	6	22
Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	50	38	91	78
Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 57	$ 119	$ 133	$ 210
Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	37	52	75	109
Pre-TDR Recorded Investment	$ 42	$ 88	$ 105	$ 170
Post-TDR Recorded Investment	28	83	81	151
Total commercial lending [Member] | Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	4	3	6	22
Total commercial lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	3	8	3	8
Total commercial lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 21	$ 72	$ 72	$ 121
Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	2,769	2,661	5,386	5,727
Pre-TDR Recorded Investment	$ 86	$ 80	$ 155	$ 169
Post-TDR Recorded Investment	83	77	149	159
Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	47	30	88	70
Total consumer lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 36	$ 47	$ 61	$ 89
Commercial [Member] | Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	27	29	57	63
Pre-TDR Recorded Investment	$ 38	$ 48	$ 91	$ 89
Post-TDR Recorded Investment	25	47	75	85
Commercial [Member] | Total commercial lending [Member] | Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	4	3	5	3
Commercial [Member] | Total commercial lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	2	4	2	4
Commercial [Member] | Total commercial lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 19	$ 40	$ 68	$ 78
Commercial Real Estate [Member] | Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	9	23	17	46
Pre-TDR Recorded Investment	$ 4	$ 40	$ 14	$ 81
Post-TDR Recorded Investment	3	36	6	66
Commercial Real Estate [Member] | Total commercial lending [Member] | Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment			1	19
Commercial Real Estate [Member] | Total commercial lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	1	4	1	4
Commercial Real Estate [Member] | Total commercial lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 2	$ 32	$ 4	$ 43
Equipment Lease Financing [Member] | Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	1		1
Home Equity [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	818	561	1,530	1,392
Pre-TDR Recorded Investment	$ 57	$ 40	$ 102	$ 92
Post-TDR Recorded Investment	55	38	97	85
Home Equity [Member] | Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	27	9	50	29
Home Equity [Member] | Total consumer lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 28	$ 29	$ 47	$ 56
Residential Real Estate [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	78	161	148	280
Pre-TDR Recorded Investment	$ 12	$ 22	$ 20	$ 40
Post-TDR Recorded Investment	12	22	21	40
Residential Real Estate [Member] | Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	6	7	11	13
Residential Real Estate [Member] | Total consumer lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 6	$ 15	$ 10	$ 27
Credit Card [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	1,641	1,717	3,204	3,568
Pre-TDR Recorded Investment	$ 14	$ 14	$ 26	$ 29
Post-TDR Recorded Investment	13	14	25	28
Credit Card [Member] | Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 13	$ 14	$ 25	$ 28
Other Consumer [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | loans	232	222	504	487
Pre-TDR Recorded Investment	$ 3	$ 4	$ 7	$ 8
Post-TDR Recorded Investment	3	3	6	6
Other Consumer [Member] | Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	1		2
Other Consumer [Member] | Total consumer lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 2	$ 3	$ 4	$ 6