Share-Based Compensation Plans - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Shares
Outstanding at beginning of period (in shares)	788,000	723,000	672,000
Granted (in shares)	130,000	156,000	174,000
Exercised (in shares)	(38,000)	(90,000)	(79,000)
Expired or cancelled (in shares)	(28,000)	(1,000)	(44,000)
Outstanding at end of period (in shares)	852,000	788,000	723,000
Exercisable (in shares)	510,000	455,000	426,000
Wtd. Avg. Exercise Price Per Share
Outstanding at beginning of period (in dollars per share)	$ 91	$ 87	$ 85
Granted (in dollars per share)	92	93	84
Exercised (in dollars per share)	93	59	65
Expired or cancelled (in dollars per share)	123	54	91
Outstanding at end of period (in dollars per share)	90	91	87
Exercisable (in dollars per share)	$ 89	$ 90	$ 82
Wtd. Avg. Remaining Contractual Term and Aggregate Intrinsic Value
Outstanding (in years)	6 years 1 month 6 days	6 years 2 months 12 days	6 years 1 month 6 days
Exercisable (in years)	4 years 9 months 18 days	4 years 6 months	4 years 6 months
Outstanding	$ 8	$ 4	$ 10
Exercised	0	3	2
Exercisable	$ 6	$ 3	$ 8