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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
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	$ 119,912		$ 119,912		$ 116,486
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	637		637		721
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	155	$ 101	336	$ 252
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	112,668		112,668		111,705
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	620		620		699
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	152	100	331	250
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	63,281		63,281		64,292
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	533		533		591
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	148	96	321	228
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	11,084		11,084		9,773
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	87		87		108
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	4	4	10	23
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	35,251		35,251		34,895
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	1	0	0
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	3,052		3,052		2,745
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	(1)	0	(1)
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	3,220		3,220		2,529
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	11		11		9
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	2	1	4	2
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	3,220		3,220		2,529
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	11		11		9
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	2	1	4	2
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	4,024		4,024		2,252
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	6		6		$ 13
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	$ 1	$ 0	$ 1	$ 0