Asset Quality (Credit Card and Other Consumer Loan Classes Asset Quality Indicators) (Details) $ in Millions	Dec. 31, 2015 USD ($)		Dec. 31, 2014 USD ($)		Dec. 31, 2013 USD ($)
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 206,696	[1]	$ 204,817	[1]	$ 195,613
% of Loans	100.00%		100.00%
Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 4,862		$ 4,612
Credit Card [Member] | High Risk [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 34		$ 35
Credit Card [Member] | High Risk [Member] | Ohio [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	17.00%		17.00%
Credit Card [Member] | High Risk [Member] | Pennsylvania [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	15.00%		16.00%
Credit Card [Member] | High Risk [Member] | Michigan [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	8.00%		9.00%
Credit Card [Member] | High Risk [Member] | New Jersey [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	8.00%		7.00%
Credit Card [Member] | High Risk [Member] | Florida [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	7.00%		6.00%
Credit Card [Member] | High Risk [Member] | Illinois [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	6.00%		7.00%
Credit Card [Member] | High Risk [Member] | Indiana [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	6.00%		6.00%
Credit Card [Member] | High Risk [Member] | Maryland [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	4.00%
Credit Card [Member] | High Risk [Member] | North Carolina [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	4.00%		4.00%
Credit Card [Member] | High Risk [Member] | All Other States Maximum [Member]
Financing Receivable, Recorded Investment [Line Items]
% of Loans	4.00%		4.00%
Credit Card [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 4,862		$ 4,612
% of Loans	100.00%		100.00%
Weighted average FICO score	734		732
Credit Card [Member] | FICO Score - Greater than 719 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 2,936		$ 2,717
% of Loans	60.00%		59.00%
Credit Card [Member] | FICO Score - 650 to 719 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 1,346		$ 1,288
% of Loans	28.00%		28.00%
Credit Card [Member] | FICO Score - 620 to 649 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 202		$ 203
% of Loans	4.00%		4.00%
Credit Card [Member] | FICO Score - Less than 620 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 227		$ 239
% of Loans	5.00%		5.00%
Credit Card [Member] | No FICO Score Available Or Required [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 151		$ 165
% of Loans	3.00%		4.00%
Other Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 21,746		$ 22,753
Other Consumer Loans [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 14,533		$ 14,319
% of Loans	100.00%		100.00%
Weighted average FICO score	744		744
Other Consumer Loans [Member] | FICO Score - Greater than 719 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 9,371		$ 9,156
% of Loans	65.00%		64.00%
Other Consumer Loans [Member] | FICO Score - 650 to 719 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 3,534		$ 3,459
% of Loans	24.00%		24.00%
Other Consumer Loans [Member] | FICO Score - 620 to 649 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 523		$ 528
% of Loans	4.00%		4.00%
Other Consumer Loans [Member] | FICO Score - Less than 620 [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 604		$ 619
% of Loans	4.00%		4.00%
Other Consumer Loans [Member] | No FICO Score Available Or Required [Member] | Using FICO Credit Metric [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 501		$ 557
% of Loans	3.00%		4.00%
Other Consumer Loans [Member] | Other Internal Credit Metrics [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 7,213		$ 8,434

[1] Our consolidated assets at December 31, 2015 included the following for which we have elected the fair value option: Federal funds sold and resale agreements of $137 million, Loans held for sale of $1.5 billion, Loans of $.9 billion, and Other assets of $521 million. Our consolidated assets at December 31, 2014 included the following for which we have elected the fair value option: Federal funds sold and resale agreements of $155 million, Loans held for sale of $2.2 billion, Loans of $1.0 billion, and Other assets of $412 million.