Supplemental Disclosures (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Summary of current accrued liabilities
Other	$ 2,452	$ 3,597
Total accrued liabilities	40,214	59,179
Accrued evaluated and unproved and unevaluated property costs [Member]
Summary of current accrued liabilities
Total accrued liabilities	28,828	45,592
Accrued support equipment and facilities costs [Member]
Summary of current accrued liabilities
Total accrued liabilities	317	1,382
Accrued stock-based compensation [Member]
Summary of current accrued liabilities
Total accrued liabilities	19	65
Accrued lease operating expenses [Member]
Summary of current accrued liabilities
Total accrued liabilities	5,376	5,218
Accrued interest on borrowings under Credit Agreement [Member]
Summary of current accrued liabilities
Total accrued liabilities	163	255
Accrued asset retirement obligations [Member]
Summary of current accrued liabilities
Total accrued liabilities	760	660
Accrued partners share of joint interest charges [Member]
Summary of current accrued liabilities
Total accrued liabilities	$ 2,299	$ 2,410