Loans and ACL (Schedule of Retail Credit Exposure, Credit Risk Profile Based on Payment Activity) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Loans and leases	$ 115,625	$ 114,603
Direct Retail Lending, Excluding Covered [Member]
Loans and leases	16,128	15,817
Direct Retail Lending, Excluding Covered [Member] | Performing Financing Receivable [Member]
Loans and leases	16,018	15,685
Direct Retail Lending, Excluding Covered [Member] | Nonperforming Financing Receivable [Member]
Loans and leases	110	132
Retail Revolving Credit, Excluding Covered [Member]
Loans and leases	2,333	2,330
Retail Revolving Credit, Excluding Covered [Member] | Performing Financing Receivable [Member]
Loans and leases	2,333	2,330
Retail Revolving Credit, Excluding Covered [Member] | Nonperforming Financing Receivable [Member]
Loans and leases	0	0
Retail Residential Mortgage, Excluding Covered [Member]
Loans and leases	24,037	24,272
Retail Residential Mortgage, Excluding Covered [Member] | Performing Financing Receivable [Member]
Loans and leases	23,799	24,003
Retail Residential Mortgage, Excluding Covered [Member] | Nonperforming Financing Receivable [Member]
Loans and leases	238	269
Retail Sales Finance, Excluding Covered [Member]
Loans and leases	9,132	7,736
Retail Sales Finance, Excluding Covered [Member] | Performing Financing Receivable [Member]
Loans and leases	9,127	7,729
Retail Sales Finance, Excluding Covered [Member] | Nonperforming Financing Receivable [Member]
Loans and leases	5	7
Retail Other Lending Subsidiaries, Excluding Covered [Member]
Loans and leases	6,672	5,999
Retail Other Lending Subsidiaries, Excluding Covered [Member] | Performing Financing Receivable [Member]
Loans and leases	6,605	5,916
Retail Other Lending Subsidiaries, Excluding Covered [Member] | Nonperforming Financing Receivable [Member]
Loans and leases	$ 67	$ 83