Stock Compensation - Stock Options (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	15	19
Granted (in shares)	2	3
Exercised (in shares)	(1)	(6)
Forfeitures and expirations (in shares)	(1)	(1)
Outstanding, end of period (in shares)	15	15
Exercisable, end of period (in shares)	10	8
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding, beginning of period, weighted-average exercise price (in dollars per share)	$ 62	$ 58
Granted, weighted-average exercise price (in dollars per share)	73	76
Exercised, weighted-average exercise price (in dollars per share)	57	56
Forfeitures and expirations, weighted-average exercise price (in dollars per share)	70	67
Outstanding, end of period, weighted-average exercise price (in dollars per share)	64	62
Exercisable, end of period, weighted-average exercise price (in dollars per share)	$ 60	$ 58
Outstanding, end of period, weighted-average remaining contractual term	6 years 9 months 18 days	7 years 2 months 12 days
Exercisable, end of period, weighted-average remaining contractual term	5 years 9 months 18 days	6 years 1 month 6 days
Outstanding, end of period, aggregate intrinsic value	$ 37	$ 226
Exercisable, end of period, aggregate intrinsic value	$ 37	$ 168
Weighted-average fair value of options granted (in dollars per share)	$ 10.14	$ 9.44