Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stock-based compensation awards
Stock-based compensation expense, before tax (in dollars)	$ 58	$ 55	$ 169	$ 169
Risk-free interest rates, low end of range (as a percent)			0.06%	1.21%
Risk-free interest rates, high end of range (as a percent)			1.41%	1.39%
Rate of volatilities, Minimum			29.20%	24.50%
Rate of volatilities, Maximum			45.80%	29.70%
Assumptions used in determining the fair value of the stock-based awards
Weighted-average dividend yield (as a percent)			2.60%	2.47%
Weighted-average volatility (as a percent)			32.90%	25.70%
Rate of volatilities, Minimum			29.20%	24.50%
Rate of volatilities, Maximum			45.80%	29.70%
Risk-free interest rates, low end of range (as a percent)			0.06%	1.21%
Risk-free interest rates, high end of range (as a percent)			1.41%	1.39%
Weighted-average expected lives (in years)			8 years	8 years
Unrecognized compensation cost related to nonvested stock-based compensation awards (in dollars)	$ 175		$ 175
Term of amortization of unrecognized compensation cost over weighted-average remaining requisite service periods (in years)			1 year 10 months 24 days
Stock Options
Stock-based compensation awards
Shares Granted (in shares)			1,084,821	1,913,888
Weighted-Average Fair Value Per Share (in dollars per share)			$ 56.30	$ 25.98
Weighted-Average Grant Date Stock Price (in dollars per share)	$ 219.76	$ 127.60	219.76	127.60
RSUs
Stock-based compensation awards
Weighted-Average Grant Date Stock Price (in dollars per share)	219.76	127.60	$ 219.76	$ 127.60
Shares Granted (in shares)			448,311	705,287
Weighted-Average Fair Value Per Share (in dollars per share)			$ 219.76	$ 127.60
PRSUs
Stock-based compensation awards
Weighted-Average Grant Date Stock Price (in dollars per share)	$ 219.76	$ 127.60	$ 219.76	$ 127.60
Shares Granted (in shares)			266,894	371,641
Weighted-Average Fair Value Per Share (in dollars per share)			$ 219.76	$ 127.60