Stock-Based Compensation (Additional Information Regarding Options Outstanding And Exercisable) (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares | shares	4,842
Options Exercisable, Number of Shares | shares	1,982
$0.00 - $45.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit	$ 0.00
Exercise price range, upper limit	$ 45.00
Options Outstanding, Number of Shares | shares	99
Options Outstanding, Weighted Average Remaining Contractual Life	4 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 40.39
Options Exercisable, Number of Shares | shares	99
Options Exercisable, Weighted Average Exercise Price	$ 40.39
$45.01 - $90.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit	45.01
Exercise price range, upper limit	$ 90.00
Options Outstanding, Number of Shares | shares	731
Options Outstanding, Weighted Average Remaining Contractual Life	1 year 10 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 64.76
Options Exercisable, Number of Shares | shares	730
Options Exercisable, Weighted Average Exercise Price	$ 64.71
$90.01 - $115.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit	90.01
Exercise price range, upper limit	$ 115.00
Options Outstanding, Number of Shares | shares	1,973
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 4 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 96.39
Options Exercisable, Number of Shares | shares	760
Options Exercisable, Weighted Average Exercise Price	$ 96.16
$115.01 - $145.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower limit	115.01
Exercise price range, upper limit	$ 145.00
Options Outstanding, Number of Shares | shares	2,039
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 3 months 18 days
Options Outstanding, Weighted Average Exercise Price	$ 119.32
Options Exercisable, Number of Shares | shares	393
Options Exercisable, Weighted Average Exercise Price	$ 124.48