Stock-Based Compensation - Stock Options (Details) - Stock Options - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Stock Option Program
Balance at the beginning of the period	39,235,557
Granted - Annual	5,529,544
Exercised	(4,947,316)
Canceled	(185,120)
Balance at the end of the period	39,632,665
Options exercisable	28,278,569
Options exercisable, exercise price	$ 85.94
Weighted average exercise price - Beginning balance	90.38
Weighted average exercise price - Granted - Annual	165.91
Weighted average exercise price - Exercised	83.44
Weighted average exercise price - Canceled	127.13
Weighted average exercise price - Ending balance	$ 101.62
Weighted average remaining contractual life for options outstanding	68 months
Weighted average remaining contractual life for options exercisable	54 months
Aggregate intrinsic value for options outstanding	$ 1,723
Aggregate intrinsic value for options exercisable	$ 1,579
Expiration of annual grants	10 years
Compensation expense yet to be recognized	$ 86
Expense recognition period	23 months
Total intrinsic value of stock options exercised	$ 393	$ 437
Cash received from options exercised	413	642
Tax benefit realized from exercise of stock options	$ 145	$ 161
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	$ 165.94
Risk-free interest rate (as a percent)	1.50%
Dividend yield (as a percent)	2.50%
Expected volatility (as a percent)	20.10%
Expected life	76 months
Black-Scholes fair value	$ 23.98