Additional Information (Schedule of Additional Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Research and development expense	$ 241	$ 203	$ 186
Advertising expense	29	27	25
Interest expense	727	754	808
Interest income	(31)	(13)	(4)
Interest related to NPM Adjustment Items	9	6	13
Interest and other debt expense, net	705	747	817
Rent expense	$ 43	$ 53	$ 48