Financial Instruments And Concentration Of Credit Risk (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Concentration Risk [Line Items]
Concentration Risk Customer Accounts Receivable	One of the most significant credit risks is the ultimate realization of accounts receivable. This risk is mitigated by (i) sales to well established companies, (ii) ongoing credit evaluation of customers, and (iii) frequent contact with customers, thus enabling management to monitor current changes in business operations and to respond accordingly. Management considers these concentrations of credit risks in establishing our allowance for doubtful accounts and believes these allowances are adequate. The Company had two customers whose gross accounts receivable exceeded 10% of total gross accounts receivable as of December 31, 2017. One customer represented 19% of our total gross accounts receivable and the second customer represented 11%.
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Unrealized gain on derivative, net of tax	$ 1,192	$ 286	$ 0
Interest Rate Swap [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Interest rate swap notional amount	$ 155,300	163,900
Fixed interest rate	1.4935%
Fair value of interest rate swap	$ 2,000	500
Unrealized gain on interest rate swap	1,500	500
Unrealized gain on derivative, net of tax	$ 900	$ 300
Accounts Receivable [Member] | Largest Customer Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	19.00%
Accounts Receivable [Member] | Second Largest Customer Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%