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Stock-Based Compensation - Narrative (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) plan shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Other information
Allocated Share-based Compensation Expense	$ 3,200,000	$ 4,400,000	$ 4,700,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 1,800,000
Number of equity stock based compensation | plan	2
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Maximum [Member] | Employees And Directors [Member] | Employee Stock Option [Member]
Other information
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Long-Term Incentive Plan [Member] | Employee Stock Option [Member]
Other information
Share Based Compensation Arrangement By Share Based Payment Award Exercisable Period From Date Of Grant	10 years
Long-Term Incentive Plan [Member] | Maximum [Member]
Other information
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized to Director's (in shares) | shares	900,000
Performance awards [Member]
Other information
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	2 years 9 months 18 days
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 2,600,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 7 months 6 days
Performance awards [Member] | Minimum [Member]
Weighted-Average Grant Date Fair Value
Potential Payout As a Percentage of Target Shares	0.00%
Performance awards [Member] | Maximum [Member]
Weighted-Average Grant Date Fair Value
Potential Payout As a Percentage of Target Shares	200.00%
Other information
Allocated Share-based Compensation Expense	$ (700,000)
Time Vested Stock Awards [Member]
Other information
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 4.4
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 7 months 6 days
Time Vested Stock Awards [Member] | Employees [Member]
Other information
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Time Vested Stock Awards [Member] | Minimum [Member] | Non-Employee Directors [Member]
Other information
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
Time Vested Stock Awards [Member] | Maximum [Member] | Non-Employee Directors [Member]
Other information
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	3 years
Time Vested Activity [Member] | Minimum [Member] | Employees And Directors [Member] | Employee Stock Option [Member]
Other information
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Time Vested Activity [Member] | Maximum [Member] | Employees And Directors [Member] | Employee Stock Option [Member]
Other information
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years

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Represents the number of equity stock based compensation.

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The percentage of target shares, an employee can earn, under the plan.

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Unrecognized cost of unvested share-based compensation awards.

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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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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, 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 (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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