Stock Options and Other Share-Based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock Option
Expected term in years	6 years 3 months 18 days	6 years 1 month 6 days	6 years
Volatility	21.70%	21.90%	30.30%
Risk-free interest rate based on zero coupon U.S. treasury note	1.60%	1.40%	1.90%
Dividend yield	4.50%	3.60%	3.30%
Weighted-average fair value per option granted (in dollars per share)	$ 9.53	$ 13.89	$ 25.86
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning balance (in shares)	94,292
Shares, Granted (in shares)	30,913
Shares, Exercised (in shares)	(8,589)
Shares, Forfeited (in shares)	(4,341)
Outstanding, ending balance (in shares)	112,275	94,292
Shares, Exercisable at December 31, 2015 (in shares)	71,153
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted-Average Exercise Price, Outstanding at January 1, 2015 (in dollars per share)	$ 96.67
Weighted-Average Exercise Price, Granted (in dollars per share)	83.31
Weighted-Average Exercise Price, Exercised (in dollars per share)	75.57
Weighted-Average Exercise Price, Forfeited (in dollars per share)	86.81
Weighted-Average Exercise Price, Outstanding at December 31, 2016 (in dollars per share)	94.99	$ 96.67
Weighted-Average Exercise Price, Exercisable at December 31, 2016 (in dollars per share)	$ 97.32
Average Remaining Contractual Term, Outstanding at December 31, 2016 (in years)	6 years 1 month 17 days
Average Remaining Contractual Term, Exercisable at December 31, 2016 (in years)	4 years 7 months 28 days
Aggregate Intrinsic Value, Outstanding at December 31, 2016	$ 2,550
Aggregate Intrinsic Value, Exercisable at December 31, 2016	$ 1,450