Debt (Debt) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term Debt	$ 10,591	$ 10,425
Debt, Current	103	104
Long-term Debt, Excluding Current Maturities	(10,488)	(10,321)
Corporate Debt Securities [Member]
Debt Instrument [Line Items]
Long-term Debt	5,892	5,892
Notes Payable, Other Payables [Member]
Debt Instrument [Line Items]
Long-term Debt	1,865	1,691
Loans Payable [Member]
Debt Instrument [Line Items]
Long-term Debt	1,638	1,646
Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt	975	972
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 221	$ 224