Stock-Based Compensation - Stock Options (Details) - Stock Options - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Stock Option Program
Balance at the beginning of the period	38,552,445
Granted - Annual	5,591,727
Exercised	(7,318,470)
Canceled	(189,747)
Balance at the end of the period	36,635,955
Options exercisable	25,622,123
Options exercisable, exercise price	$ 95.54
Weighted average exercise price - Beginning balance	102.01
Weighted average exercise price - Granted - Annual	147.99
Weighted average exercise price - Exercised	86.67
Weighted average exercise price - Canceled	148.16
Weighted average exercise price - Ending balance	$ 111.85
Weighted average remaining contractual life for options outstanding	72 months
Weighted average remaining contractual life for options exercisable	59 months
Aggregate intrinsic value for options outstanding	$ 2,358
Aggregate intrinsic value for options exercisable	$ 2,067
Expiration of annual grants	10 years
Compensation expense yet to be recognized	$ 87
Expense recognition period	22 months
Total intrinsic value of stock options exercised	$ 573	$ 393
Cash received from options exercised	630	413
Tax benefit realized from exercise of stock options	$ 212	$ 145
Maximum
Stock Option Program
Vesting period	3 years
Minimum
Stock Option Program
Vesting period	1 year
Annual Stock Option Program
Share- based compensation assumptions
Weighted average exercise price	$ 147.87
Risk-free interest rate (as a percent)	1.50%
Dividend yield (as a percent)	2.50%
Expected volatility (as a percent)	20.80%
Expected life	77 months
Black-Scholes fair value	$ 22.47