Finance Receivables And Loans, Net (Schedule Of Pass And Criticized Credit Quality Indicators Of Finance Receivables) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	$ 99,123	$ 99,055	$ 118,986
Commercial Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	34,437	35,519
Commercial Loan [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	32,703	33,835
Commercial Loan [Member] | Criticized Member
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	1,734	1,684
Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	29,255	30,270
Commercial And Industrial Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	27,905	28,978
Commercial And Industrial Automobile [Member] | Criticized Member
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	1,350	1,292
Commercial And Industrial Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	0	0
Commercial And Industrial Mortgage [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	0	0
Commercial And Industrial Mortgage [Member] | Criticized Member
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	0	0
Commercial And Industrial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	2,562	2,697
Commercial And Industrial Other [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	2,296	2,417
Commercial And Industrial Other [Member] | Criticized Member
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	266	280
Commercial Real Estate Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	2,620	2,552
Commercial Real Estate Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	2,502	2,440
Commercial Real Estate Automobile [Member] | Criticized Member
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	118	112
Commercial Real Estate Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	0	0
Commercial Real Estate Mortgage [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	0	0
Commercial Real Estate Mortgage [Member] | Criticized Member
Financing Receivable, Recorded Investment [Line Items]
Finance receivables and loans, net	$ 0	$ 0