Share-Based Payments (Share Options) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 7,700	$ 5,000	$ 4,100
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance at beginning of year (in shares)	23,429
Granted (in shares)	0	0	0
Forfeited (in shares)	(577)
Expired (in shares)	(2,284)
Exercised (in shares)	(2,242)
Balance at end of year (in shares)	18,326	23,429
Total Exercisable Shares	18,326
Weighted Average Exercise Price at beginning of year	$ 45.98
Weighted Average Exercise Price, Forfeited	54.70
Weighted Average Exercise Price, Expired	135.97
Weighted Average Exercise Price, Exercised	10.05
Weighted Average Exercise Price at end of year	38.88	$ 45.98
Exercisable, Weighted Average Exercise Price	$ 38.88
Weighted Average Remaining Contractual Term	7 months 27 days
Aggregate Intrinsic Value	$ 214
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number	18,326
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 38.88
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	7 months 27 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 214
Exercisable, Weighted Average Remaining Contractual Term	7 months 27 days
Exercisable, Aggregate Intrinsic Value	$ 214
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 67	$ 232	$ 85
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Abstract]
Number of Option Shares	18,326
Weighted Average Remaining Contractual Life	7 months 27 days
Weighted Average Exercise Price of Option Shares	$ 38.88
Number of Exercisable Option Shares	18,326
Weighted Average Exercise Price of Exercisable Option Shares	$ 38.88
Stock-based compensation expense	$ 7,745	$ 5,009	$ 4,090
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares	0
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range From 0.00 To 9.99 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Abstract]
Range of Exercise Prices, Lower Limit	$ 0.00
Range of Exercise Prices, Upper Limit	$ 9.99
Number of Option Shares	6,393
Weighted Average Remaining Contractual Life	1 year 3 months 24 days
Weighted Average Exercise Price of Option Shares	$ 9.91
Number of Exercisable Option Shares	6,393
Weighted Average Exercise Price of Exercisable Option Shares	$ 9.91
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range From 40.00 To 49.99 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Abstract]
Range of Exercise Prices, Lower Limit	40.00
Range of Exercise Prices, Upper Limit	$ 49.99
Number of Option Shares	349
Weighted Average Remaining Contractual Life	5 months 25 days
Weighted Average Exercise Price of Option Shares	$ 44.49
Number of Exercisable Option Shares	349
Weighted Average Exercise Price of Exercisable Option Shares	$ 44.49
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range From 50.00 To 136.93 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Abstract]
Range of Exercise Prices, Lower Limit	50.00
Range of Exercise Prices, Upper Limit	$ 136.93
Number of Option Shares	11,584
Weighted Average Remaining Contractual Life	3 months 19 days
Weighted Average Exercise Price of Option Shares	$ 54.70
Number of Exercisable Option Shares	11,584
Weighted Average Exercise Price of Exercisable Option Shares	$ 54.70
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award, Exercisable Period	5 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Share Based Compensation Arrangement By Share Based Payment Award, Maximum Term	10 years

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Share Based Compensation Arrangement By Share Based Payment Award, Maximum Term

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. 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 exercise price, at which grantee can acquire shares reserved for issuance, for 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 price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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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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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

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The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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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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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. 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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Number of options vested.

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Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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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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