Long-Term Debt (Uncommitted Funding Facilities) (Details) (Uncommitted Funding Facilities [Member], USD $) In Billions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Outstanding	$ 6.1	$ 7.4
Unused capacity	3.7	3.9
Total capacity	9.8	11.3
Bank Funding Member | Secured Debt [Member]
Debt Instrument [Line Items]
Outstanding	4.3	5.4
Unused capacity	2.8	3.2
Total capacity	7.1	8.6
Bank Funding Member | Federal Reserve Bank Advances [Member] | Secured Debt [Member] | North American Automotive Finance Operations [Member]
Debt Instrument [Line Items]
Outstanding	0	0
Unused capacity	2.0	3.2
Total capacity	2.0	3.2
Bank Funding Member | Federal Home Loan Bank Advances [Member] | Secured Debt [Member] | North American Automotive Finance Operations [Member]
Debt Instrument [Line Items]
Outstanding	4.3	5.4
Unused capacity	0.8	0
Total capacity	5.1	5.4
Nonbank Funding [Member]
Debt Instrument [Line Items]
Outstanding	1.8	2.0
Unused capacity	0.9	0.7
Total capacity	2.7	2.7
Nonbank Funding [Member] | Secured Debt [Member] | International Automotive Finance Operations [Member]
Debt Instrument [Line Items]
Outstanding	0.1	0.1
Unused capacity	0.1	0.1
Total capacity	0.2	0.2
Nonbank Funding [Member] | Secured Debt [Member] | Mortgage Operations [Member]
Debt Instrument [Line Items]
Outstanding	0	0
Unused capacity	0	0.1
Total capacity	0	0.1
Nonbank Funding [Member] | Unsecured Debt [Member] | International Automotive Finance Operations [Member]
Debt Instrument [Line Items]
Outstanding	1.7	1.9
Unused capacity	0.8	0.5
Total capacity	$ 2.5	$ 2.4