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Market Concentrations and Risks (Details) $ in Thousands, lb in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 USD ($) lb Customer Distributor | Dec. 31, 2016 USD ($) Customer Distributor | Dec. 31, 2015 Customer Distributor
Concentration Risk [Line Items] |  |  |
Number of customers | Customer | 10 | 10 | 10
Number of distributors | Distributor | 6 | 6 | 6
Senior Subordinated Notes [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Fair value of debt instrument | $ 1,619,300 | $ 1,693,200 |
Total senior subordinated notes | $ 1,584,232 | $ 1,643,448 |
Copper [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Committed amounts to purchase | lb | 2.3 |  |
Aggregate cost | $ 7,000 |  |
Recorded unconditional purchase obligation fixed cost | $ (500) |  |
Customer Concentration Risk [Member] | Consolidated Revenues [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 35.00% | 33.00% | 33.00%
Labor Force Concentration Risk [Member] | Workforce Subject to Collective Bargaining Arrangements [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 21.00% |  |
Labor Force Concentration Risk [Member] | Workforce Subject to Collective Bargaining Arrangements Expiring within One Year [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage | 16.00% |  |

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