Organization and Summary of Significant Accounting Policies (Details) (USD $)
| 3 Months Ended | 9 Months Ended | |
|---|
Sep. 30, 2011 | Sep. 30, 2010 | Sep. 30, 2011 | Sep. 30, 2010 | Dec. 31, 2010 |
|---|
| Change in ARO (asset retirement obligation) | | | | | |
| Beginning Balance | | | $ 108,000,000 | | |
| Accretion expense | | | 8,000,000 | | |
| Additions | | | 9,000,000 | | |
| Settlements | | | (5,000,000) | | |
| Ending Balance | 120,000,000 | | 120,000,000 | | |
| Less: Current portion of ARO | (10,000,000) | | (10,000,000) | | (11,000,000) |
| Total long-term ARO | 110,000,000 | | 110,000,000 | | 97,000,000 |
| Organization and Summary of Significant Accounting Policies (Textuals) [Abstract] | | | | | |
| Realized interest income and gains on investment securities | 300,000 | 400,000 | 1,000,000 | 1,000,000 | |
| Crude oil inventory (in barrels) | 384,000 | | 384,000 | | 277,000 |
| Crude oil inventory | 29,000,000 | | 29,000,000 | | 15,000,000 |
| Capitalization of internal costs per full cost method of accouting | 30,000,000 | 17,000,000 | 81,000,000 | 53,000,000 | |
| Discount rate | | | 10.00% | | |
| Unweighted average commodity price of natural gas based on first-day-of-the-month prices for the prior 12 months (per MMBtu) | 4.16 | | 4.16 | | |
| Unweighted average commodity price of oil based on first-day-of-the-month prices for the prior 12 months (per barrel) | $ 94.48 | | $ 94.48 | | |