Equity Compensation (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Equity Compensation [Abstract]
Maximum shares of common stock	20,000,000
Maximum annual shares awarded to employee	500,000
Shares available for granting additional awards	7,086,915
Unrecognized compensation cost of non-vested equity compensation awards	$ 11,100
Unrecognized compensation cost of non-vested equity compensation awards expected to be recognized over a weighted average period (years)	2 years
Number of options granted	0	0
Intrinsic value of stock options exercised	$ 484	$ 1,600
Stock Options
Equity Compensation [Abstract]
Maximum period for exercisable options (years and days)	10 years 1 day
Stock Options \| Minimum
Equity Compensation [Abstract]
Vesting period (months)	24 months
Stock Options \| Maximum
Equity Compensation [Abstract]
Vesting period (months)	72 months
Restricted Stock
Equity Compensation [Abstract]
Fair value of awards vested	$ 793	467
Restricted Stock \| Minimum
Equity Compensation [Abstract]
Vesting period (months)	12 months
Restricted Stock \| Maximum
Equity Compensation [Abstract]
Vesting period (months)	60 months
Performance Shares
Equity Compensation [Abstract]
Fair value of awards vested	$ 1,300	$ 1,000
Performance Shares \| Minimum
Equity Compensation [Abstract]
Vesting period (months)	12 months
Performance Shares \| Maximum
Equity Compensation [Abstract]
Vesting period (months)	60 months

Unrecognized cost of unvested share-based compensation awards.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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 maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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

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The period of time, measured from grant date, before which an equity-based award expires as specified in the award agreement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The maximum number of shares that can be awarded per participant per year under an employee share-based payment plan.

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