CONSOLIDATED BALANCE SHEETS [Parenthetical] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable, Current	$ 605	$ 432
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	231,391	209,466
Finite-Lived Intangible Assets, Accumulated Amortization	$ 5,183	$ 4,684
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	4,000,000	4,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	100,000,000	100,000,000
Common Stock, Shares, Issued	16,464,757	16,333,139
Common Stock, Shares, Outstanding	16,464,757	16,333,139