Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stock-based compensation awards
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum			24.50%	25.10%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum			29.70%	38.70%
Stock-based compensation expense, before tax (in dollars)	$ 67	$ 68	$ 114	$ 113
Assumptions used in determining the fair value of the stock-based awards
Weighted-average dividend yield (as a percent)			2.47%	2.56%
Weighted-average volatility (as a percent)			25.70%	29.10%
Risk-free interest rates, low end of range (as a percent)			1.21%	2.48%
Risk-free interest rates, high end of range (as a percent)			1.39%	2.68%
Weighted-average expected lives (in years)			8 years	7 years
Unrecognized compensation cost related to nonvested stock-based compensation awards (in dollars)	$ 228		$ 228
Term of amortization of unrecognized compensation cost over weighted-average remaining requisite service periods (in years)			1 year 9 months 18 days
Stock Options
Stock-based compensation awards
Shares Granted (in shares)			1,913,888	1,499,524
Weighted-Average Fair Value Per Share (in dollars per share)			$ 25.98	$ 40.98
Weighted-Average Grant Date Stock Price (in dollars per share)	$ 127.60	$ 138.35	127.60	138.35
RSUs
Stock-based compensation awards
Weighted-Average Grant Date Stock Price (in dollars per share)	127.60	138.35	$ 127.60	$ 138.35
Shares Granted (in shares)			705,287	657,389
Weighted-Average Fair Value Per Share (in dollars per share)			$ 127.60	$ 138.35
PRSUs
Stock-based compensation awards
Weighted-Average Grant Date Stock Price (in dollars per share)	$ 127.60	$ 138.35	$ 127.60	$ 138.35
Shares Granted (in shares)			371,641	342,097
Weighted-Average Fair Value Per Share (in dollars per share)			$ 127.60	$ 138.35