Deferred Compensation Agreements and Stock-Based Compensation (Details) - LTR Plan - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred compensation agreements
Percentage of participant's annual earned bonus deferred	50.00%
Period of deferral of annual earned bonus	1 year
Total deferred compensation liability	$ 5,700		$ 4,500
Maximum percentage of participant's earned bonus amount up to which common stock can be purchased in a stock purchase plan	16.67%
Percentage of average market closing prices used in determining number of common stock that could be purchased by participants	75.00%	75.00%	75.00%

No definition available.

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- Definition

Represents the maximum percentage of participant's prior year earned bonus amount up to which common stock can be purchased under the deferred compensation arrangement.

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- Definition

Represents percentage of average market closing prices used in determining number of common stock that could be purchased by participants.

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No definition available.

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- Definition

Represents the percentage of participant's annual earned bonus deferred under the deferred compensation arrangement.

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No definition available.

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- Definition

Represents the period of deferral of annual earned bonus under the deferred compensation arrangement.

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No definition available.

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

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No definition available.

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- Details

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