Stock Transactions And Stock-Based Compensation (Summary Of Options Outstanding) (Details) shares in Millions	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Range One
Options, exercise price, lower range limit	$ 36.87
Options, exercise price, upper range limit	$ 52.96
Outstanding, shares (in millions) | shares	1.0
Outstanding, average exercise price	$ 43.97
Outstanding, average remaining life (in years)	2 years
Exercisable, shares (in millions) | shares	1.0
Exercisable, average exercise price	$ 43.96
Range Two
Options, exercise price, lower range limit	52.97
Options, exercise price, upper range limit	$ 66.70
Outstanding, shares (in millions) | shares	2.7
Outstanding, average exercise price	$ 63.94
Outstanding, average remaining life (in years)	4 years
Exercisable, shares (in millions) | shares	2.1
Exercisable, average exercise price	$ 63.41
Range Three
Options, exercise price, lower range limit	66.71
Options, exercise price, upper range limit	$ 99.32
Outstanding, shares (in millions) | shares	3.7
Outstanding, average exercise price	$ 82.40
Outstanding, average remaining life (in years)	6 years
Exercisable, shares (in millions) | shares	2.0
Exercisable, average exercise price	$ 78.94
Range Four
Options, exercise price, lower range limit	99.33
Options, exercise price, upper range limit	$ 131.04
Outstanding, shares (in millions) | shares	5.2
Outstanding, average exercise price	$ 106.64
Outstanding, average remaining life (in years)	8 years
Exercisable, shares (in millions) | shares	1.1
Exercisable, average exercise price	$ 104.20
Range Five
Options, exercise price, lower range limit	131.05
Options, exercise price, upper range limit	$ 234.68
Outstanding, shares (in millions) | shares	3.3
Outstanding, average exercise price	$ 156.93
Outstanding, average remaining life (in years)	9 years
Exercisable, shares (in millions) | shares	0.1
Exercisable, average exercise price	$ 139.44