Loans - Consumer, Excluding Credit Card Loans, Other Consumer Loans Financial Effects of Modification (Details) (Consumer, excluding credit card, USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Business Banking Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance of loans that redefaulted within one year of permanent modification	$ 4,000,000	$ 10,000,000	$ 18,000,000	$ 33,000,000
Business Banking Loans | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of years before payment default under a modified loan			1 year
Auto Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance of loans that redefaulted within one year of permanent modification	$ 11,000,000	$ 13,000,000	$ 33,000,000	$ 41,000,000
Auto Loans | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of years before payment default under a modified loan			1 year
Scored Auto and Business Banking Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of payments past due for deemed payment default			2