Short-Term Borrowings (Schedule of Short-term Debt) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Short-term Debt [Line Items]
Demand Notes	$ 2,958	$ 2,756
Short-term Bank Loans and Notes Payable	857	1,613
Federal Home Loan Bank, Advances, Short-term	0	1,400
Other Short-term Borrowings	2,195	1,911
Short-term Borrowings, Total	6,010	7,680
Unsecured Debt [Member]
Short-term Debt [Line Items]
Demand Notes	2,958	2,756
Short-term Bank Loans and Notes Payable	857	1,613
Federal Home Loan Bank, Advances, Short-term	0	0
Other Short-term Borrowings	188	146
Short-term Borrowings, Total	4,003	4,515
Secured Debt [Member]
Short-term Debt [Line Items]
Demand Notes	0	0
Short-term Bank Loans and Notes Payable	0	0
Federal Home Loan Bank, Advances, Short-term		1,400
Other Short-term Borrowings	2,007	1,765
Short-term Borrowings, Total	$ 2,007	$ 3,165