Share-Based Compensation Plans (Company's Shareholder Approved Plans) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-Based Compensation Plans [Abstract]
Outstanding at January 1, Shares	360,364	454,994	648,034
Exercised, Shares	81,200	94,630	187,940
Forfeited/Cancelled/Expired, Shares			5,100
Outstanding at December 31, Shares	279,164	360,364	454,994
Exercisable at December 31, Shares	279,164	360,364	410,694
Outstanding at January 1, Weighted-Average Exercise Price/Share	$ 84.10	$ 84.88	$ 85.61
Exercised, Weighted- Average Exercise Price/Share	84.99	87.84	87.31
Forfeited/Cancelled/Expired, Weighted- Average Exercise Price/Share			88.25
Outstanding at December 31, Weighted-Average Exercise Price/Share	83.84	84.10	84.88
Exercisable at December 31, Weighted-Average Exercise Price/Share	$ 83.84	$ 84.10	$ 84.50
Outstanding at December 31, Weighted-Average Remaining Contractual Term	1 year 10 months 24 days	2 years 8 months 12 days	3 years 8 months 12 days
Exercisable at December 31, Weighted-Average Remaining Contractual Term	1 year 10 months 24 days	2 years 8 months 12 days	3 years 6 months
Outstanding at December 31, Aggregate Intrinsic Value	$ 37,386	$ 49,428	$ 59,843
Exercisable at December 31, Aggregate Intrinsic Value	$ 37,386	$ 49,428	$ 54,169

No definition available.

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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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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

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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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Number of share options (or share units) exercised during the current period.

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