Income Taxes (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||||
|---|---|---|---|---|---|---|
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Sep. 30, 2014 |
Sep. 30, 2015 |
Sep. 30, 2014 |
|
| Income Tax Disclosure [Abstract] | ||||||
| Effective income tax rate percentage | 12.10% | 35.80% | 24.90% | 36.40% | ||
| Deferred tax assets valuation allowance | $ 66,600 | $ 66,600 | ||||
| Income Tax Expense (Benefit) | (33,305) | $ 16,504 | (149,045) | $ 36,675 | ||
| Changes in Future Income Tax Expense Estimates on Future Cash Flows Related to Proved Oil and Gas Reserves | $ 33,300 | $ 82,700 | $ 24,300 | $ 140,300 | ||