Investments In Marketable Securities (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments, Debt and Equity Securities [Abstract]
Realized losses on the sale of available-for-sale securities	$ 0	$ 0	$ 0
Other-than-temporary impairment of marketable securities	0	0	0
Gross proceeds from sales of available-for-sale securities	$ 4,406,000,000	$ 6,489,000,000	$ 6,119,000,000