Derivative Financial Instruments (Schedule of Open Commodity Derivative Positions) (Details) (USD $) | 9 Months Ended |
|---|---|
Sep. 30, 2011 | |
Q4 2011 [Member] | Bbl [Member] | Open Oil Derivative Positions [Member] | Price Collars [Member] | |
| Volume per day | 45,000 |
| Weighted Average Floor Price | 75.00 |
| Weighted Average Ceiling Price | 108.89 |
Q4 2011 [Member] | Bbl [Member] | Open Oil Derivative Positions [Member] | Call Options Sold [Member] | |
| Volume per day | 19,500 |
| Weighted Average Price | 95.00 |
Q4 2011 [Member] | Bbl [Member] | Open NGL Derivative Positions [Member] | NGL Basis Swap [Member] | |
| Volume per day | 332 |
| Weighted average differential between WTI and Natural Gasoline Dollars Per Barrel | (9.75) |
Q4 2011 [Member] | MMBtu [Member] | Open Natural Gas Derivative Positions [Member] | Price Swaps [Member] | |
| Volume per day | 712,500 |
| Weighted Average Price | 5.51 |
Q4 2011 [Member] | MMBtu [Member] | Open Natural Gas Derivative Positions [Member] | Price Collars [Member] | |
| Volume per day | 287,935 |
| Weighted Average Floor Price | 4.66 |
| Weighted Average Ceiling Price | 5.07 |
Q4 2011 [Member] | MMBtu [Member] | Open Natural Gas Derivative Positions [Member] | Gas Basis Swap [Member] | |
| Volume per day | 150,000 |
| Weighted Average Differential Between Henry Hub and Panhandle Eastern Pipeline Dollars Per Millions of British Thermal Units | (0.33) |
Q1-Q4 2012 [Member] | Bbl [Member] | Open Oil Derivative Positions [Member] | Price Swaps [Member] | |
| Volume per day | 22,000 |
| Weighted Average Price | 107.17 |
Q1-Q4 2012 [Member] | Bbl [Member] | Open Oil Derivative Positions [Member] | Price Collars [Member] | |
| Volume per day | 54,000 |
| Weighted Average Floor Price | 85.74 |
| Weighted Average Ceiling Price | 126.42 |
Q1-Q4 2012 [Member] | Bbl [Member] | Open Oil Derivative Positions [Member] | Call Options Sold [Member] | |
| Volume per day | 19,500 |
| Weighted Average Price | 95.00 |
Q1-Q4 2012 [Member] | Bbl [Member] | Open NGL Derivative Positions [Member] | NGL Basis Swap [Member] | |
| Volume per day | 500 |
| Weighted average differential between WTI and Natural Gasoline Dollars Per Barrel | (10.10) |
Q1-Q4 2012 [Member] | MMBtu [Member] | Open Natural Gas Derivative Positions [Member] | Price Swaps [Member] | |
| Volume per day | 325,000 |
| Weighted Average Price | 5.09 |
Q1-Q4 2012 [Member] | MMBtu [Member] | Open Natural Gas Derivative Positions [Member] | Price Collars [Member] | |
| Volume per day | 490,000 |
| Weighted Average Floor Price | 4.75 |
| Weighted Average Ceiling Price | 5.57 |
Q1-Q4 2012 [Member] | MMBtu [Member] | Open Natural Gas Derivative Positions [Member] | Call Options Sold [Member] | |
| Volume per day | 487,500 |
| Weighted Average Price | 6.00 |
Q1-Q4 2013 [Member] | Bbl [Member] | Open Oil Derivative Positions [Member] | Price Collars [Member] | |
| Volume per day | 7,000 |
| Weighted Average Floor Price | 90.00 |
| Weighted Average Ceiling Price | 125.12 |
Q1-Q4 2013 [Member] | Bbl [Member] | Open NGL Derivative Positions [Member] | NGL Basis Swap [Member] | |
| Volume per day | 500 |
| Weighted average differential between WTI and Natural Gasoline Dollars Per Barrel | (6.80) |