Stock Transactions And Stock-Based Compensation (Summary Of Options Outstanding) (Details) shares in Millions	12 Months Ended
	Dec. 31, 2017 $ / shares shares
$19.89 to $38.63
Options, exercise price, lower range limit	$ 19.89
Options, exercise price, upper range limit	$ 38.63
Outstanding, shares (in millions) | shares	3.3
Outstanding, average exercise price	$ 30.61
Outstanding, average remaining life (in years)	2 years
Exercisable, shares (in millions) | shares	3.3
Exercisable, average exercise price	$ 30.58
$38.64 to $53.03
Options, exercise price, lower range limit	38.64
Options, exercise price, upper range limit	$ 53.03
Outstanding, shares (in millions) | shares	3.3
Outstanding, average exercise price	$ 44.40
Outstanding, average remaining life (in years)	5 years
Exercisable, shares (in millions) | shares	2.7
Exercisable, average exercise price	$ 43.68
$53.04 to $65.94
Options, exercise price, lower range limit	53.04
Options, exercise price, upper range limit	$ 65.94
Outstanding, shares (in millions) | shares	3.2
Outstanding, average exercise price	$ 60.32
Outstanding, average remaining life (in years)	6 years
Exercisable, shares (in millions) | shares	1.1
Exercisable, average exercise price	$ 59.55
$65.95 to $76.11
Options, exercise price, lower range limit	65.95
Options, exercise price, upper range limit	$ 76.11
Outstanding, shares (in millions) | shares	4.5
Outstanding, average exercise price	$ 66.59
Outstanding, average remaining life (in years)	8 years
Exercisable, shares (in millions) | shares	0.9
Exercisable, average exercise price	$ 66.74
$76.12 to $92.42
Options, exercise price, lower range limit	76.12
Options, exercise price, upper range limit	$ 92.42
Outstanding, shares (in millions) | shares	4.5
Outstanding, average exercise price	$ 85.69
Outstanding, average remaining life (in years)	9 years
Exercisable, shares (in millions) | shares	0.1
Exercisable, average exercise price	$ 81.31