Marketable Securities And Cash Equivalents (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended	1 Months Ended
	Jun. 30, 2012	Jun. 30, 2012 Equity Securities [Member]	Dec. 31, 2011 Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses that arose within the last 12 months	$ 4
Number of available-for-sale equity securities with unrealized losses (in securities)	1
Market value of the investments that have been in an unrealized loss position for less than 12 months		97
Other than temporary impairment losses, investments, available-for-sale securities		$ 12	$ 13
Number of avaliable-for-sale securities with other than temporary impairment charges		1