Marketable Securities - Schedule of Marketable Securities (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 165	$ 109
Unrealized Gain (Loss)	4	1
Fair Value	169	110
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	39	27
Unrealized Gain (Loss)	0	0
Fair Value	39	27
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	35	30
Unrealized Gain (Loss)		(1)
Fair Value	35	29
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	25	21
Unrealized Gain (Loss)
Fair Value	25	21
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	66	31
Unrealized Gain (Loss)	4	2
Fair Value	$ 70	$ 33