Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments - Fair Value (Details)

v3.19.2
Financial Instruments - Fair Value (Details) - Derivatives designated as hedging instrument - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Derivative assets:    
Total derivative assets $ 24,852 $ 20,768
Derivative liabilities:    
Total derivative liabilities 4,090 2,026
Cash flow hedging    
Derivative assets:    
Total derivative assets 70 1,925
Cash flow hedging | Prepaid and other current assets | Natural gas swaps    
Derivative assets:    
Total derivative assets 0 21
Cash flow hedging | Prepaid and other current assets | Interest rate caps    
Derivative assets:    
Total derivative assets 69 1,358
Cash flow hedging | Other long-term assets | Interest rate caps    
Derivative assets:    
Total derivative assets 1 546
Cash flow hedging | Accrued liabilities | Natural gas swaps    
Derivative liabilities:    
Total derivative liabilities 750 36
Cash flow hedging | Other long-term liabilities | Natural gas swaps    
Derivative liabilities:    
Total derivative liabilities 283 148
Cash flow hedging | Other long-term liabilities | Interest rate caps    
Derivative liabilities:    
Total derivative liabilities 3,057 1,842
Net investment hedging    
Derivative assets:    
Total derivative assets 24,782 18,843
Net investment hedging | Prepaid and other current assets | Cross currency swaps    
Derivative assets:    
Total derivative assets 5,574 5,499
Net investment hedging | Other long-term assets | Cross currency swaps    
Derivative assets:    
Total derivative assets $ 19,208 $ 13,344