Commitments and Contingencies (Schedule of Other Commitments) (Details) $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended | 19 Months Ended | 21 Months Ended |
Jan. 31, 2020USD ($) | Jun. 30, 2020USD ($) | Mar. 31, 2020USD ($) | Sep. 30, 2019 | Jun. 30, 2018USD ($) | Mar. 31, 2018 | Dec. 31, 2019USD ($) | Dec. 31, 2018USD ($) | Nov. 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 | | | | | | | | | | | | | | | | | 17.37% | | | | |
Fourth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | | | | | 0.00% | | | | | | |
Antidumping Duties [Member] | Other Current Assets [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Receivable | | | $ 500 | | | | | | | | | | | | | | | | | | |
Antidumping Duties [Member] | Other Assets [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Receivable | | | 1,300 | | | | | | | | | | | | | | | | | | |
Antidumping Duties [Member] | Other Noncurrent Liabilities [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Liability | | | 10,300 | | | | | | | | | | | | | | | | | | |
Antidumping Duties [Member] | First Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate | | | | | 0.73% | 5.92% | | | | | | | | | | | | | | 0.73% | |
Contingent Liability | | | | | | | | $ 800 | | | | | | | | | | | | | |
Contingent Receivable | | | $ 1,300 | | | | | $ 1,300 | | | | | | | | | | | | | |
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 | | | 13.74% | | | | | | | | | | | | | | | | 3.92% | | |
Contingent Liability | | | $ 4,100 | | | | | | | | | | | | | | | | | | |
Antidumping Duties [Member] | Second Annual Review [Member] | Scenario, Plan [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate | | 3.92% | | | | | | | | | | | | | | | | | | | |
Decrease in contingent liability | | $ 3,900 | | | | | | | | | | | | | | | | | | | |
Antidumping Duties [Member] | Third Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Liability | | | 4,700 | | | | | | | | | | | | | | | | | | |
Antidumping Duties [Member] | Fourth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | | | | | 0.00% | | | | | | |
Antidumping Duties [Member] | Fifth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | | | 0.00% | | | | | | | | |
Antidumping Duties [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Liability | | | 1,500 | | | | $ 800 | | | | | | | | | | | | | | |
Contingent Receivable | | | $ 500 | | | | | | | | | | | | | | | | | | |
Antidumping Duties [Member] | Seventh Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | | 0.00% | | | | | | | | | | | | |
Loss Contingency Preliminary Purchase Price Of Anti dumping Duty Rate | 0 | | | | | | | | | | | | | | | | | | | | |
Antidumping Duties [Member] | Minimum [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate | | | | 0.00% | | | 0.00% | | | | | | | | | | | | | | |
Antidumping Duties [Member] | Maximum [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate | | | 42.57% | 42.57% | | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Other Current Assets [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Receivable | | | $ 100 | | | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Other Assets [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Receivable | | | 300 | | | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Other Current Liabilities [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Liability | | | 40 | | | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | First and Second Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | | | | | | | | | 1.50% |
Contingent Receivable | | | 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 | | | | | | | | | | | | | | | | | | 1.38% | | | |
Contingent Receivable | | | 50 | | | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Fourth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | | | | 1.06% | | | | | |
Contingent Receivable | | | 20 | | | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Fifth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Receivable | | | 70 | | | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Liability | | | $ 40 | | | | $ 400 | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Seventh Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Contingent Liability | $ 2,000 | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Preliminary Purchase Price Of Countervailing Duty Rate | 24.61 | | | | | | | | | | | | | | | | | | | | |
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 [Member] | First and Second Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | | | | | | | | | 0.83% |
Countervailing Duties [Member] | Minimum [Member] | Fifth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | | 0.11% | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Minimum [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | 2.96% | | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Maximum [Member] | First and Second Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | | | | | | | | | 0.99% |
Countervailing Duties [Member] | Maximum [Member] | Fifth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | | 0.85% | | | | | | | | | | | | | | | | |
Countervailing Duties [Member] | Maximum [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | 3.10% | | | | | | | | | | | | | | | | | |
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] | Fifth 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% | | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | 42.57% | | | | | | | | | | |
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] | Fifth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | | 0.83% | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | | 0.11% | | | | | | | |
Contingent Receivable | | | | | $ 70 | | | | | | | | | | | | | | | | |
Deposit One [Member] | Countervailing Duties [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | 0.99% | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | 3.10% | | | | | | | | | |
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] | Fifth 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% | | | | | | | | | | |
Loss Contingency Modified 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] | Fifth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | | 0.99% | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | | | 0.85% | | | | | | | |
Deposit Two [Member] | Countervailing Duties [Member] | Sixth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | 1.38% | | | | | | | | | |
Loss Contingency Modified Purchase Price Of Countervailing Duties Rate | | | | | | | | | | | | 2.96% | | | | | | | | | |
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] | Fifth Annual Review [Member] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingencies [Line Items] | | | | | | | | | | | | | | | | | | | | | |
Loss Contingency Purchase Price Of Antidumping Duty Rate | | | | | | | | | | | | | 17.37% | | | | | | | | |