Supplemental Disclosures (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Summary of current accrued liabilities
Other	$ 2,410	$ 2,852
Total accrued liabilities	59,179	25,439
Accrued evaluated and unproved and unevaluated property costs [Member]
Summary of current accrued liabilities
Total accrued liabilities	45,592	18,185
Accrued support equipment and facilities costs [Member]
Summary of current accrued liabilities
Total accrued liabilities	1,382	216
Accrued cost to issue equity [Member]
Summary of current accrued liabilities
Total accrued liabilities		332
Accrued stock-based compensation [Member]
Summary of current accrued liabilities
Total accrued liabilities	65	2,860
Accrued lease operating expenses [Member]
Summary of current accrued liabilities
Total accrued liabilities	5,218	575
Accrued interest on borrowings under Credit Agreement [Member]
Summary of current accrued liabilities
Total accrued liabilities	255	34
Accrued asset retirement obligations [Member]
Summary of current accrued liabilities
Total accrued liabilities	660	334
Accrued partners' share of joint interest charges [Member]
Summary of current accrued liabilities
Total accrued liabilities	$ 3,597	$ 51