Securitization and Variable Interest Entities (Schedule of Net Credit Losses for Securitized and Other Financial Assets Managed Together) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	$ 628	$ 1,175	$ 1,604	$ 2,859
On-Balance Sheet Loans [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	48	110	133	290
Off-Balance Sheet Loans [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	485	1,010	1,234	2,299
Whole-Loan Transactions [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	95	55	237	270
Consumer Loans Auto Financing Receivable [Member] | On-Balance Sheet Loans [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	70	60	144	172
Consumer Loans Auto Financing Receivable [Member] | Off-Balance Sheet Loans [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	0	0	0	0
Residential Mortgage [Member] | On-Balance Sheet Loans [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	(3)	33	18	81
Private Placement [Member] | Off-Balance Sheet Loans [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	485	1,010	1,234	2,299
Commercial Automobile [Member] | On-Balance Sheet Loans [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	(1)	8	(1)	11
Commercial Finance Receivables And Loans, Mortgage [Member] | On-Balance Sheet Loans [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	0	9	(1)	25
Commercial Other [Member] | On-Balance Sheet Loans [Member]
Net Credit Losses for Securitized and Other Financial Assets Managed Together [Line Items]
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	$ (18)	$ 0	$ (27)	$ 1