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		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 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	$ 110,184		$ 110,184		$ 105,681
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	577		577		655
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	101	$ 86	252	$ 223
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	106,611		106,611		101,951
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	554		554		617
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	100	85	250	218
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	62,142		62,142		58,085
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	410		410		457
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	96	83	228	204
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	9,258		9,258		7,926
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	123		123		151
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	4	8	23	20
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	33,026		33,026		34,022
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	21		21		9
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	1	1	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	2,185		2,185		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)	(7)	(1)	(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	2,212		2,212		2,801
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	6		6		5
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	1	0	2	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	2,212		2,212		2,801
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	6		6		5
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	1	0	2	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	1,361		1,361		929
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	17		17		$ 33
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	$ 0	$ 1	$ 0	$ 4