Basis of Presentation and Significant Accounting Policies and Practices - Additional Information (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Advertising expense					$ 44	$ 46	$ 45
Antidilutive securities excluded from computation of earnings per share, Amount (in shares)					0	12	11
Maximum length to maturity of a security, from the investment date, where it is classified as cash and cash equivalent					90 days
Length to maturity from the investment date of a security where the length of time is too short to be classified as a short-term investment					90 days
Consigned inventory	$ 334				$ 334	$ 275
Excess tax benefit from share-based payments	$ 17	$ 50	$ 40	$ 43	$ 150	$ 90	$ 110