Marketable Securities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 security
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses that arose within the last 12 months	$ 2
Number of available-for-sale equity securities with unrealized losses (in securities)	1
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Market value of the investments that have been in an unrealized loss position for less than 12 months	$ 5