Stock Options and Other Share-Based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Option
Expected term in years	[1]	6 years 1 month 6 days	6 years	6 years
Volatility	[2]	21.90%	30.30%	31.30%
Risk-free interest rate based on zero coupon U.S. treasury note		1.40%	1.90%	1.20%
Dividend yield		3.60%	3.30%	3.30%
Weighted-average fair value per option granted		$ 13.89	$ 25.86	$ 24.48
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at January 1, 2015		78,341
Shares, Granted (in shares)		22,126
Shares, Exercised (in shares)		(3,104)
Shares, Forfeited (in shares)		(3,071)
Outstanding at December 31, 2015		94,292	78,341
Shares, Exercisable at December 31, 2014 (in shares)		65,657
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, 2014 (in dollars per share)		$ 93.59
Weighted-Average Exercise Price, Granted (in dollars per share)		103.71
Weighted-Average Exercise Price, Exercised (in dollars per share)		62.06
Weighted-Average Exercise Price, Forfeited (in dollars per share)		103.70
Weighted-Average Exercise Price, Outstanding at December 31, 2014 (in dollars per share)		96.67	$ 93.59
Weighted-Average Exercise Price, Exercisable at December 31, 2014 (in dollars per share)		$ 91.85
Average Remaining Contractual Term, Outstanding at December 31, 2014 (in years)		5 years 9 months 29 days
Average Remaining Contractual Term, Exercisable at December 31, 2014 (in years)		4 years 7 months 10 days
Aggregate Intrinsic Value, Outstanding at December 31, 2014		$ 467
Aggregate Intrinsic Value, Exercisable at December 31, 2014		$ 467

[1] Expected term is based on historical exercise and postvesting cancellation data.

[2] Volatility rate is based on historical stock prices over an appropriate period, generally equal to the expected term.