Borrowings and Contractual Commitments Short-Term Borrowings (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Short-term Debt [Line Items]
Federal Home Loan Bank, Advances, Short-term	$ 4,000	$ 1,500
Other Short-term Borrowings	5,788	3,303
Federal Home Loan Bank Advances [Member]
Short-term Debt [Line Items]
Short-term Debt, Weighted Average Interest Rate	0.21%	0.34%
Master Notes [Member]
Short-term Debt [Line Items]
Other Short-term Borrowings	1,554	1,512
Short-term Debt, Weighted Average Interest Rate	0.28%	0.30%
Dealer Collateral [Member]
Short-term Debt [Line Items]
Other Short-term Borrowings	232	282
Short-term Debt, Weighted Average Interest Rate	0.10%	0.17%
Other Short Term Borrowings [Member]
Short-term Debt [Line Items]
Other Short-term Borrowings	$ 2	$ 9
Short-term Debt, Weighted Average Interest Rate	2.70%	2.70%