Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 160	$ 164
Unrealized Gains (Losses)	2	5
Fair Value	162	169
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	38	38
Unrealized Gains (Losses)	0	0
Fair Value	38	38
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 42	$ 36
Unrealized Gains (Losses)
Fair Value	$ 42	$ 36
Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 18	23
Unrealized Gains (Losses)
Fair Value	$ 18	23
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	62	67
Unrealized Gains (Losses)	2	5
Fair Value	$ 64	$ 72