Asset Quality (Consumer Real Estate Secured Asset Quality Indicators) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
% of Loans	100.00%	100.00%
Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	$ 16,076	$ 16,600
Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	11,378	12,228
Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	14,883	13,028
Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	$ 42,337	$ 41,856
Total home equity and residential real estate loans | New Jersey | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	17.00%	16.00%
Total home equity and residential real estate loans | Pennsylvania | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	13.00%	14.00%
Total home equity and residential real estate loans | Illinois | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	13.00%	12.00%
Total home equity and residential real estate loans | Ohio | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	9.00%	10.00%
Total home equity and residential real estate loans | Florida | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	6.00%	7.00%
Total home equity and residential real estate loans | Maryland | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	8.00%	6.00%
Total home equity and residential real estate loans | Michigan | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	4.00%	4.00%
Total home equity and residential real estate loans | North Carolina | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	5.00%	4.00%
Total home equity and residential real estate loans | All Other States Maximum | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	4.00%	4.00%
Total home equity and residential real estate loans | All Other States | High Risk
Financing Receivable, Recorded Investment [Line Items]
% of Loans	25.00%	27.00%
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Greater than 660 | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	$ 108	$ 161
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Greater than 660 | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	385	629
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Greater than 660 | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	126	174
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Greater than 660 | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	619	964
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Less than or equal to 660 | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	21	32
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Less than or equal to 660 | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	64	110
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Less than or equal to 660 | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	23	35
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Less than or equal to 660 | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	108	177
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Missing | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	1	1
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Missing | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	5	9
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Missing | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	1	2
LTV greater than or equal to 125% and updated FICO scores | FICO Score- Missing | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	7	12
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Greater than 660 | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	300	394
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Greater than 660 | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	842	1,190
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Greater than 660 | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	253	345
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Greater than 660 | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	1,395	1,929
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Less than or equal to 660 | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	46	66
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Less than or equal to 660 | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	143	211
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Less than or equal to 660 | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	45	76
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Less than or equal to 660 | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	234	353
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Missing | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	2	3
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Missing | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	9	10
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Missing | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	5	7
LTV greater than or equal to 100% to less than 125% and updated FICO scores | FICO Score- Missing | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	16	20
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Greater than 660 | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	331	453
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Greater than 660 | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	890	1,100
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Greater than 660 | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	324	463
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Greater than 660 | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	1,545	2,016
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Less than or equal to 660 | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	55	77
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Less than or equal to 660 | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	134	171
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Less than or equal to 660 | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	55	78
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Less than or equal to 660 | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	244	326
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Missing | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	2	1
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Missing | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	9	8
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Missing | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	4	6
LTV greater than or equal to 90% to less than 100% and updated FICO scores | FICO Score- Missing | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	15	15
LTV less than 90% and updated FICO scores | FICO Score- Greater than 660 | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	13,954	14,047
LTV less than 90% and updated FICO scores | FICO Score- Greater than 660 | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	8,066	7,913
LTV less than 90% and updated FICO scores | FICO Score- Greater than 660 | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	13,445	11,153
LTV less than 90% and updated FICO scores | FICO Score- Greater than 660 | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	35,465	33,113
LTV less than 90% and updated FICO scores | FICO Score- Less than or equal to 660 | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	1,214	1,323
LTV less than 90% and updated FICO scores | FICO Score- Less than or equal to 660 | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	774	822
LTV less than 90% and updated FICO scores | FICO Score- Less than or equal to 660 | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	507	586
LTV less than 90% and updated FICO scores | FICO Score- Less than or equal to 660 | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	2,495	2,731
LTV less than 90% and updated FICO scores | FICO Score- Missing | Home Equity Line of Credit | 1st Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	42	42
LTV less than 90% and updated FICO scores | FICO Score- Missing | Home Equity Line of Credit | 2nd Liens
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	57	55
LTV less than 90% and updated FICO scores | FICO Score- Missing | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	95	102
LTV less than 90% and updated FICO scores | FICO Score- Missing | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans	$ 194	199
Missing LTV and updated FICO scores | FICO Score- Greater than 660 | Residential Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans		1
Missing LTV and updated FICO scores | FICO Score- Greater than 660 | Total home equity and residential real estate loans
Financing Receivable, Recorded Investment [Line Items]
Loans - Excluding purchased impaired and government insured or guaranteed loans		$ 1