4. Derivatives - Schedule of Recognized Gains (Losses) for Derivatives (Details) - Commodity Contracts [Member] - Non Designated Derivative Instruments [Member] - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Realized Gains (Losses) | $ 2,242 | $ (251) | $ 2,152 | $ (101) |
| Unrealized Gains (Losses) | $ (1,383) | $ (824) | $ (483) | $ (1,451) |
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of open derivatives, commodity, or energy contracts, held at each balance sheet date, that was included in earnings for the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|