Derivative Instruments and Hedging Activity (Summary of Information Regarding Deferred Put Premium Liabilities) (Details) - USD ($) $ in Thousands |
12 Months Ended | |||
|---|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Derivative Instruments And Hedging Activities Disclosure [Abstract] | ||||
| Current commodity derivative premium put payable | $ 3,194 | $ 2,481 | ||
| Long-term commodity derivative premium payable | 2,788 | 4,702 | ||
| Total unamortized put premium liabilities | $ 5,982 | $ 7,183 | $ 5,982 | $ 7,183 |
| Put Premium Liabilities [Roll Forward] | ||||
| Put premium liabilities, beginning balance | 7,183 | 7,145 | ||
| Amortization of put premium liabilities | (2,295) | (145) | ||
| Additional put premium liabilities | 1,094 | 183 | ||
| Put premium liabilities, ending balance | $ 5,982 | $ 7,183 | ||