Commitments and Contingencies (Schedule of Other Commitments) (Details) - USD ($) $ in Thousands | 1 Months Ended | 9 Months Ended | 10 Months Ended | 12 Months Ended | 19 Months Ended | 21 Months Ended |
May 31, 2018 | Sep. 30, 2018 | Sep. 30, 2018 | Dec. 31, 2017 | Nov. 30, 2017 | Dec. 31, 2016 | Nov. 30, 2016 | Dec. 31, 2015 | Nov. 30, 2015 | Dec. 31, 2014 | Nov. 30, 2014 | Dec. 31, 2013 | Nov. 30, 2013 | Nov. 30, 2012 | Dec. 31, 2012 |
Third Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate, Maximum | | | | | | | | | | | | 17.37% | | | | | |
Contingent Liability | | | $ 5,500 | $ 5,500 | | | | | | | | | | | | | |
Fourth Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate, Maximum | | | | | | | | | | 0.00% | | | | | | | |
Contingent Receibable | | | 2,100 | 2,100 | | | | | | | | | | | | | |
Antidumping Duties [Member] | Other Current Assets [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Contingent Receibable | | | 4,900 | 4,900 | | | | | | | | | | | | | |
Antidumping Duties [Member] | Other Assets [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Contingent Receibable | | | 1,300 | 1,300 | | | | | | | | | | | | | |
Antidumping Duties [Member] | Other Noncurrent Liabilities [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Contingent Liability | | | 9,600 | 9,600 | | | | | | | | | | | | | |
Antidumping Duties [Member] | First Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate, Maximum | | 5.92% | | | | | | | | | | | | | 0.73% | [1] | |
Contingent Liability | | $ 800 | | | | | | | | | | | | | | | |
Contingent Receibable | [1] | | $ 1,300 | 1,300 | | | | | | | | | | | | | |
Antidumping Duties [Member] | First Annual Review [Member] | Scenario, Plan [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate, Maximum | | | 0.73% | | | | | | | | | | | | | | |
Antidumping Duties [Member] | Second Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | | | | 3.30% | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate, Maximum | | | | | | | | | | | | | | 13.74% | | | |
Contingent Liability | | | $ 4,100 | 4,100 | | | | | | | | | | | | | |
Antidumping Duties [Member] | Fith Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate, Maximum | [2] | | | | | | | 0.00% | | | | | | | | | |
Contingent Receibable | [2] | | 2,800 | $ 2,800 | | | | | | | | | | | | | |
Antidumping Duties [Member] | Seventh Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | 0.00% | | | | | | | | | | | | | |
Countervailing Duties [Member] | Other Assets [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Contingent Receibable | | | 340 | $ 340 | | | | | | | | | | | | | |
Countervailing Duties [Member] | First and Second Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | | | | | 1.50% |
Contingent Receibable | | | 200 | 200 | | | | | | | | | | | | | |
Countervailing Duties [Member] | Third Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | 1.50% | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate, Maximum | | | | | | | | | | | | | 1.38% | | | | |
Contingent Receibable | | | 50 | 50 | | | | | | | | | | | | | |
Countervailing Duties [Member] | Fourth Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate, Maximum | | | | | | | | | | | 1.06% | | | | | | |
Contingent Receibable | | | 20 | 20 | | | | | | | | | | | | | |
Countervailing Duties [Member] | Fith Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Contingent Receibable | [3] | | $ 70 | $ 70 | | | | | | | | | | | | | |
Countervailing Duties [Member] | Eighth Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | 1.06% | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Minimum | First and Second Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate, Maximum | | | | | | | | | | | | | | | | | 0.83% |
Countervailing Duties [Member] | Minimum | Fith Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate, Maximum | [3] | | | | | | | | 0.11% | | | | | | | | |
Countervailing Duties [Member] | Maximum | First and Second Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate, Maximum | | | | | | | | | | | | | | | | | 0.99% |
Countervailing Duties [Member] | Maximum | Fith Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate, Maximum | [3] | | | | | | | | 0.85% | | | | | | | | |
Deposit One [Member] | Antidumping Duties [Member] | First Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | | | | | 6.78% | | |
Deposit One [Member] | Antidumping Duties [Member] | Third Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | | 3.30% | | | | | |
Deposit One [Member] | Antidumping Duties [Member] | Fourth Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | | | 5.92% | | | | | | | |
Deposit One [Member] | Antidumping Duties [Member] | Fith Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | 5.92% | | | | | | | | | |
Deposit One [Member] | Antidumping Duties [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | 17.37% | | | | | | | | | | | |
Deposit One [Member] | Countervailing Duties [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | 1.50% | | | | | | |
Deposit One [Member] | Countervailing Duties [Member] | Fith Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | 0.83% | | | | | | | | |
Deposit One [Member] | Countervailing Duties [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | 0.99% | | | | | | | | | | |
Deposit One [Member] | Countervailing Duties [Member] | Seventh Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | 1.38% | | | | | | | | | | | | |
Deposit Two [Member] | Antidumping Duties [Member] | First Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | | | | | 3.30% | | |
Deposit Two [Member] | Antidumping Duties [Member] | Third Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | | 5.92% | | | | | |
Deposit Two [Member] | Antidumping Duties [Member] | Fourth Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | | | 13.74% | | | | | | | |
Deposit Two [Member] | Antidumping Duties [Member] | Fith Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | 13.74% | | | | | | | | | |
Deposit Two [Member] | Antidumping Duties [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | 0.00% | | | | | | | | | | | |
Deposit Two [Member] | Countervailing Duties [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | 0.83% | | | | | | |
Deposit Two [Member] | Countervailing Duties [Member] | Fith Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | 0.99% | | | | | | | | |
Deposit Two [Member] | Countervailing Duties [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | 1.38% | | | | | | | | | | |
Deposit Two [Member] | Countervailing Duties [Member] | Seventh Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | 1.06% | | | | | | | | | | | | |
Deposit Three [Member] | Antidumping Duties [Member] | Fith Annual Review [Member] | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | 17.37% | | | | | | | | | |
| |
[1] | In June 2018, the Court of International Trade sustained the DOC's recommendation to reduce the rate for the first annual review period to 0.73% (from 5.92%). As a result, in the second quarter of 2018 the Company reversed its $0.8 million liability and recorded a $1.3 million receivable with a corresponding reduction of Cost of Sales. | |
[2] | In July 2018, the DOC issued the final rates for review period 5 at 0.0%. As a result, in the third quarter of 2018 the Company recorded a receivable of $2.8 million with a corresponding reduction of Cost of Sales. | |
[3] | In June 2018, the DOC issued the final rates for review period 5 at 0.11% and 0.85% depending on vendor. As a result, in the second quarter of 2018 the Company recorded a receivable of $0.07 million for deposits made at previous preliminary rates, with a corresponding reduction of Cost of Sales. | |