Commitments and Contingent Liabilities (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Guarantees [Abstract]
Related liability	$ 2,000,000	$ 2,000,000	$ 3,000,000
SPC's assets in Consolidated Statements of Financial Position	927,000,000	586,000,000	365,000,000
SPC's liabilities in Consolidated Statements of Financial Position	927,000,000	586,000,000	365,000,000
Unused commitments and lines of credit for dealers	10,970,000,000	6,600,000,000	6,580,000,000
Unused commitments and lines of credit for customers	4,690,000,000	2,790,000,000	2,610,000,000
Guarantor Obligations
Guarantees, maximum potential amount of future payments	151,000,000	170,000,000	156,000,000
Guarantees with customers
Guarantor Obligations
Guarantees, maximum potential amount of future payments	151,000,000	159,000,000	139,000,000
Limited indemnity
Guarantor Obligations
Guarantees, maximum potential amount of future payments	$ 0	$ 11,000,000	$ 17,000,000