Prepaid Expenses and Other Current Assets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Prepaid Expense And Other Asset [Line Items]
Prepaid well and drilling costs	$ 2,843	$ 3,053
Prepaid Insurance	3,330	1,346
Inventory	5,127	1,629
Deferred tax asset	8,089	0
Other	1,606	2,501
Prepaid Expense and Other Assets, Current, Total	20,995	18,840
[PrepaidExpensesAndOtherCurrentAssetsMember]
Prepaid Expense And Other Asset [Line Items]
Fair market value of commodity derivatives - current	0	1,247
[PrepaidExpensesAndOtherCurrentAssetsMember] | [AlbaFieldMember]
Prepaid Expense And Other Asset [Line Items]
Deposits and other cost related to the COP Acquisition	$ 0	$ 9,064