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	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
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	$ 112,928		$ 112,928		$ 105,681
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	626		626		655
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	162	$ 150	414	$ 373
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	108,028		108,028		101,951
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	603		603		617
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	161	149	411	367
On-Balance Sheet Loans [Member] | Consumer Portfolio Segment [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	9,770		9,770		7,926
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	107		107		151
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	6	12	29	32
On-Balance Sheet Loans [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [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	63,610		63,610		58,085
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	490		490		457
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	156	137	384	341
On-Balance Sheet Loans [Member] | Commercial Portfolio Segment [Member] | Automobile Loan [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	32,322		32,322		34,022
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	6		6		9
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 Portfolio Segment [Member] | Other Financing Receivables [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	2,326		2,326		1,918
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	(1)	0	(2)	(7)
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	2,870		2,870		2,801
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	8		8		5
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	1	0	3	1
Off-Balance Sheet Loans [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [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	2,870		2,870		2,801
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	8		8		5
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	1	0	3	1
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	2,030		2,030		929
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	15		15		$ 33
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	$ 0	$ 1	$ 0	$ 5