Securitizations And Variable Interest Entities (Schedule Of Quantitative Information and Net Credit Losses about Securitized and Other Financial Assets Managed Together) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
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	$ 99,983		$ 99,983		$ 229,266
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	697		697		2,642
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	130	98	354	233
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	95,363		95,363		101,631
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	612		612		617
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	126	96	343	221
On-Balance Sheet Loans [Member] | Consumer Loans Auto Financing Receivable [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	56,450		56,450		53,715
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	384		384		351
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	115	96	288	240
On-Balance Sheet Loans [Member] | Residential Mortgage [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	8,835		8,835		12,311
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	188		188		241
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	11	2	58	12
On-Balance Sheet Loans [Member] | Commercial Automobile [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	28,452		28,452		32,822
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	40		40		24
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	0	2	0	1
On-Balance Sheet Loans [Member] | Commercial Finance Receivables And Loans, Mortgage [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		0		0
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	0		0		0
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	0	0	0	(1)
On-Balance Sheet Loans [Member] | Commercial Other [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	1,626		1,626		2,783
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	0		0		1
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	0	(4)	(3)	(31)
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	1,031		1,031		120,879
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	3		3		1,896
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	1	1	3	1
Off-Balance Sheet Loans [Member] | Consumer Loans Auto Financing Receivable [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	1,031		1,031		1,495
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	3		3		4
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	1	1	3	1
Off-Balance Sheet Loans [Member] | US Government-sponsored Enterprises [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		0		119,384
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	0		0		1,892
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	0		0
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	3,589		3,589		6,756
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	82		82		129
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	$ 3	$ 1	$ 8	$ 11