General Devaluation (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Foreign Exchange Related Charges	$ 0		$ (26)	$ (31)	$ (68)
Angola, Kwanza
Foreign Exchange Related Charges		$ (31)	(20)		(36)
Venezuelan bolívar fuerte
Foreign Exchange Related Charges					(26)
Kazakhstan, Tenge
Foreign Exchange Related Charges			$ (6)		$ (6)