Long-Term Debt (Components of Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Long-term debt	$ 14,517	$ 13,878
Less current portion of long-term debt	525	1,459
Long-term debt excluding current portion	13,992	12,419
Notes, 2.85% to 10.20%, interest payable semi-annually (average coupon interest rate 5.9%), due through 2044 [Member] | Notes [Member]
Debt Instrument [Line Items]
Long-term debt	14,475	13,836
Notes, 2.85% to 10.20%, interest payable semi-annually (average coupon interest rate 5.9%), due through 2044 [Member] | Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate percentage	2.85%	2.85%
Notes, 2.85% to 10.20%, interest payable semi-annually (average coupon interest rate 5.9%), due through 2044 [Member] | Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate percentage	10.20%	10.20%
Notes, 2.85% to 10.20%, interest payable semi-annually (average coupon interest rate 5.9%), due through 2044 [Member] | Notes [Member] | Weighted Average [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	5.90%	7.20%
Debenture, 7.75% due 2027, interest payable semi-annually [Member] | Debentures [Member]
Debt Instrument [Line Items]
Long-term debt	$ 42	$ 42
Debt instrument, interest rate percentage	7.75%	7.75%