Share-Based Compensation (Schedule Of Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Options outstanding, January 1	859,182	541,679	741,676
Options outstanding, December 31	920,346	859,182	541,679
Options exercisable, December 31	476,992
Weighted Average Exercise Price, Options outstanding, January 1	$ 70.11	$ 65.84	$ 60.43
Weighted Average Exercise Price, Options outstanding, December 31	69.24	$ 70.11	$ 65.84
Weighted Average Exercise Price, Options exercisable, December 31	$ 70.93
Weighted Average Remaining Contractual Life (Years), Options outstanding, December 31	3 years 4 months 5 days
Weighted Average Remaining Contractual Life (Years), Options exercisable, December 31	2 years 10 months 18 days
Aggregate Intrinsic Value, Options outstanding, December 31	$ 5,798
Aggregate Intrinsic Value, Options exercisable, December 31	$ 2,204
2005 Plan [Member]
Options exercised	(6,668)	(15,000)	(61,666)
Weighted Average Exercise Price, Options exercised	$ 72.11	$ 47.52	$ 52.36
2012 Plan [Member]
Options granted	560,000	495,000	470,000
Options exercised	(462,167)	(155,829)	(608,331)
Options forfeited	(30,001)	(6,668)
Weighted Average Exercise Price, Options granted	$ 64.33	$ 74.90	$ 60.78
Weighted Average Exercise Price, Options exercised	65.03	65.73	$ 65.18
Weighted Average Exercise Price, Options forfeited	$ 66.73	$ 60.52
Grant Date 2-25-2014
Options outstanding, December 31	15,000
Weighted Average Exercise Price, Options outstanding, December 31	$ 61.31
Weighted Average Remaining Contractual Life (Years), Options outstanding, December 31	1 month 26 days
Grant Date 2-20-2015
Options outstanding, December 31	50,002
Weighted Average Exercise Price, Options outstanding, December 31	$ 72.11
Weighted Average Remaining Contractual Life (Years), Options outstanding, December 31	1 year 1 month 21 days
Grant Date 2-22-2016
Options outstanding, December 31	36,668
Weighted Average Exercise Price, Options outstanding, December 31	$ 60.52
Weighted Average Remaining Contractual Life (Years), Options outstanding, December 31	2 years 1 month 24 days
Grant Date 3-8-2016
Options outstanding, December 31	26,667
Weighted Average Exercise Price, Options outstanding, December 31	$ 63.63
Weighted Average Remaining Contractual Life (Years), Options outstanding, December 31	2 years 2 months 8 days
Grant Date 2-22-2017
Options outstanding, December 31	399,170
Weighted Average Exercise Price, Options outstanding, December 31	$ 74.78
Weighted Average Remaining Contractual Life (Years), Options outstanding, December 31	3 years 1 month 24 days
Grant Date 9-1-2017
Options outstanding, December 31	10,000
Weighted Average Exercise Price, Options outstanding, December 31	$ 80.55
Weighted Average Remaining Contractual Life (Years), Options outstanding, December 31	3 years 8 months 5 days
Grant Date 2-20-2018 [Member]
Options outstanding, December 31	382,839
Weighted Average Exercise Price, Options outstanding, December 31	$ 64.33
Weighted Average Remaining Contractual Life (Years), Options outstanding, December 31	4 years 1 month 22 days

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

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