Securitizations And Variable Interest Entities (Schedule Of Quantitative Information about Securitized and Other Financial Assets Managed Together) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	$ 255,859	$ 484,248
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	2,648	27,418
Off-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	124,551	326,975
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	1,905	20,757
On-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	123,196	123,312
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	707	3,760
Whole-Loan Transactions [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	8,112	33,961
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	36	2,901
Consumer Loans Auto Financing Receivable [Member] | Off-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	1,659	0
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	2	0
Consumer Loans Auto Financing Receivable [Member] | On-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	70,847	63,884
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	388	341
Commercial Automobile [Member] | On-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	37,381	37,302
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	78	162
Commercial Finance Receivables And Loans, Mortgage [Member] | On-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	686	1,925
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	0	14
Commercial Other [Member] | On-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	2,568	1,261
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	1	1
Residential Mortgage [Member] | On-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	11,714	18,940
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	240	3,242
US Government-sponsored Enterprises [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
loans subject to conditional repurchase options	0	2,300
US Government-sponsored Enterprises [Member] | Off-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	122,892	262,984
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	1,903	9,456
Private Placement [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
loans subject to conditional repurchase options	0	132
Private Placement [Member] | Off-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	0	63,991
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	$ 0	$ 11,301