Derivative Financial Instruments (Derivatives And Hedging-Overall-Subsequent Measurement) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2019 |
Jun. 30, 2018 |
Jun. 30, 2019 |
Jun. 30, 2018 |
|
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivative, Gain (Loss) on Derivative, Net | $ (17,254) | $ (30,074) | $ (67,964) | $ (41,393) |
| Commodity Contract [Member] | Sales [Member] | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivative, Gain (Loss) on Derivative, Net | (4,619) | (38,411) | (59,130) | (45,786) |
| Commodity Contract [Member] | Cost of Sales [Member] | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivative, Gain (Loss) on Derivative, Net | (6,148) | 8,337 | (3,875) | 4,393 |
| Energy Related Derivative [Member] | Other Operating Income (Expense) [Member] | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivative, Gain (Loss) on Derivative, Net | $ (6,487) | $ 0 | $ (4,959) | $ 0 |