CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, less allowance for doubtful accounts	$ 1,354	$ 1,525
Property, plant and equipment, net of accumulated depreciation	$ 317,414	$ 289,909
Capital Stock, par value (in dollars per share)	$ 1
Capital Stock, authorized shares	50,000
Capital Stock, shares issued	18,395
Capital Stock, shares outstanding	18,255

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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