Short-Term Borrowings (Schedule of Short-term Debt) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Short-term Debt [Line Items]
Demand Notes	$ 3,092	$ 2,756
Short-term Bank Loans and Notes Payable	718	1,613
Federal Home Loan Bank, Advances, Short-term	0	1,400
Other Short-term Borrowings	2,067	1,911
Short-term Borrowings, Total	5,877	7,680
Unsecured Debt [Member]
Short-term Debt [Line Items]
Demand Notes	3,092	2,756
Short-term Bank Loans and Notes Payable	718	1,613
Federal Home Loan Bank, Advances, Short-term	0	0
Other Short-term Borrowings	153	146
Short-term Borrowings, Total	3,963	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	1,914	1,765
Short-term Borrowings, Total	$ 1,914	$ 3,165