Common Shares And Stock-Based Awards Plans (Summary Of Stock Options) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-Based Compensation [Abstract]
Number of Options, Outstanding, Beginning balance	1,197	2,580	2,437
Number of Options, Granted			289
Number of Options, Exercised	(582)	(928)	(114)
Number of Options, Forfeited or expired	(19)	(455)	(32)
Number of Options, Outstanding, Ending balance	596	1,197	2,580
Number of Options, Exercisable as of December 31, 2017	443	900	1,800
Weighted-Average Exercise Price, Outstanding, Beginning balance	$ 19.51	$ 20.49	$ 20.07
Weighted-Average Exercise Price, Granted			23.14
Weighted-Average Exercise Price, Exercised	19.28	20.29	17.39
Weighted-Average Exercise Price, Forfeited or expired	19.76	23.49	23.4
Weighted-Average Exercise Price, Outstanding, Ending balance	19.72	19.51	20.49
Weighted-Average Exercise Price, Exercisable as of December 31, 2017	$ 18.56	$ 18.53	$ 20.19
Weighted-Average Remaining Contractual Term (Years), Outstanding	5 years 3 months 11 days
Weighted-Average Remaining Contractual Term (Years), Exercisable as of December 31, 2017	3 years 7 months 24 days
Aggregate Intrinsic Value, Outstanding as of December 31, 2017	$ 5,592
Aggregate Intrinsic Value, Exercisable as of December 31, 2017	$ 4,667

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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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Net 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 grantees can acquire the shares reserved for issuance under the stock option plan.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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

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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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