Stock-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Stock Option Program
Allocated Share Based Compensation Expense	$ 144	$ 138
Stock Options
Stock Option Program
Balance at the beginning of the period	38,552,445
Granted - Annual	5,591,727
Exercised	(3,604,464)
Canceled	(43,305)
Balance at the end of the period	40,496,403
Options exercisable	29,338,088
Options exercisable, exercise price	$ 94.32
Weighted average exercise price - Beginning balance	102.01
Weighted average exercise price - Granted - Annual	147.99
Weighted average exercise price - Exercised	87.47
Weighted average exercise price - Canceled	141.28
Weighted average exercise price - Ending balance	$ 109.61
Weighted average remaining contractual life for options outstanding	74 months
Weighted average remaining contractual life for options exercisable	61 months
Aggregate intrinsic value for options outstanding	$ 2,309
Aggregate intrinsic value for options exercisable	$ 2,121
Expiration of annual grants	10 years
Compensation expense yet to be recognized	$ 126
Expense recognition period	26 months
Total intrinsic value of stock options exercised	$ 253	258
Cash received from options exercised	315	266
Tax benefit realized from exercise of stock options	$ 93	$ 96
Stock Options | Maximum
Stock Option Program
Vesting period	3 years
Stock Options | Minimum
Stock Option Program
Vesting period	1 year
Stock Options | 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