Commercial Paper and Long-Term Debt (Narrative) (Details) (USD $)				3 Months Ended				3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Commercial Paper [Member]	Mar. 31, 2014 Five Year $3.0 Billion Credit Facility [Member] Revolving Credit Facility [Member]	Mar. 31, 2014 Five Year $3.0 Billion Credit Facility [Member] Minimum [Member] Revolving Credit Facility [Member]	Mar. 31, 2014 Five Year $3.0 Billion Credit Facility [Member] Maximum [Member] Revolving Credit Facility [Member]	Mar. 31, 2014 364 Day $1.0 Billion Credit Facility [Member] Revolving Credit Facility [Member] banks	Mar. 31, 2014 364 Day $1.0 Billion Credit Facility [Member] Minimum [Member] Revolving Credit Facility [Member]	Mar. 31, 2014 364 Day $1.0 Billion Credit Facility [Member] Maximum [Member] Revolving Credit Facility [Member]	Mar. 31, 2014 Interest Rate Swap [Member]	Dec. 31, 2013 Interest Rate Swap [Member]	Mar. 31, 2014 Other Liabilities [Member] Interest Rate Swap [Member]	Dec. 31, 2013 Other Liabilities [Member] Interest Rate Swap [Member]
Other Long-term Debt	$ 135,000,000	$ 121,000,000
Other Long-term Debt, Current	43,000,000	34,000,000
Revolving bank credit facility, Amount Outstanding				0			0
Short-term Debt, Weighted Average Interest Rate			0.20%
Line of Credit, Credit Facility, Maximum Borrowing Capacity			4,000,000,000	3,000,000,000			1,000,000,000
Debt Instrument, Interest Rate During Period					1.00%	1.20%		1.00%	1.20%
Number Of Years Of Revolving Bank Credit				5 years
Credit Facility, Number of Days							364
Number of banks that comprise revolving bank credit facility (banks)				23			23
Maximum percentage of indebtedness to total net capital bank covenant				50.00%			50.00%
Derivative, Notional Amount										6,200,000,000	6,200,000,000
Interest Rate Derivative Liabilities, at Fair Value	$ 97,000,000	$ 163,000,000										$ 97,000,000	$ 163,000,000