Derivative Contracts - Derivative Gains (Losses) (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2017 |
|
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivative gain (loss) | $ 2,248 | $ 5,482 | $ 3,644 | $ 9,519 |
| Common Stock options/warrants | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivative gain (loss) | 1,916 | 444 | 3,587 | (512) |
| Notes | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivative gain (loss) | 0 | 5,069 | 0 | 10,014 |
| Forward contracts | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Derivative gain (loss) | $ 332 | $ (31) | $ 57 | $ 17 |