Stock Based Incentive Compensation Plans (Summary of activity for stock options with service conditions) (Details) - Stock options with service conditions [Member] $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Shares
Outstanding as of beginning of year (in shares) | shares	2,894,656
Granted - original (in shares) | shares	837,329
Exercised (includes shares tendered) (in shares) | shares	(146,370)
Forfeited or expired (in shares) | shares	(126,656)
Outstanding as of end of year (in shares) | shares	3,458,959
Vested or expected to vest as of end of year (in shares) | shares	3,181,759
Exercisable as of end of year (in shares) | shares	2,141,140
Summary of activity for stock options, additional disclosures [Abstract]
Weighted average exercise price as of beginning of year (in dollars per share) | $ / shares	$ 55.67
Weighted average exercise price granted - original (in dollars per share) | $ / shares	60.86
Weighted average exercise price exercised (includes shares tendered) (in dollars per share) | $ / shares	32.70
Weighted average exercise price forfeited or expired (in dollars per share) | $ / shares	62.72
Weighted average exercise price outstanding as of end of year (in dollars per share) | $ / shares	57.64
Weighted average exercise price vested or expected to vest as of end of year (in dollars per share) | $ / shares	56.93
Weighted average exercise price exercisable as of end of year (in dollars per share) | $ / shares	$ 54.26
Weighted average remaining contractual term outstanding as of end of year (in years)	6 years 5 months 15 days
Weighted average remaining contractual term vested or expected to vest as of end of year (in years)	6 years 3 months 25 days
Weighted average remaining contractual term exercisable as of end of year (in years)	5 years 1 month 13 days
Aggregate intrinsic value outstanding as of end of year | $	$ 12
Aggregate intrinsic value vested or expected to vest as of end of year | $	12
Aggregate intrinsic value exercisable as of end of year | $	$ 12