Investments In Marketable Securities (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	$ 359,000,000		$ 359,000,000
Available-for-sale Securities, Debt Securities, Noncurrent	17,000,000		17,000,000
Gain Loss On Marketable Securities
Realized losses on the sale of available-for-sale securities	0	0	0	0
Other-than-temporary impairment of marketable securities	0	0	0	0
Gross proceeds from sales of available-for-sale securities	$ 1,158,000,000	$ 619,000,000	$ 2,218,000,000	$ 2,323,000,000