Long-Term Debt (Details) (USD $) In Thousands, unless otherwise specified	Aug. 02, 2012	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2012 Borrowing Base Facility [Member]	May 31, 2012 Borrowing Base Facility [Member]	Dec. 31, 2011 Borrowing Base Facility [Member]	Dec. 31, 2011 Secured Pipeline Loan [Member]
Summary of long-term debt
Total debt	$ 7,500	$ 167,355	$ 193,000		$ 167,355	$ 176,000	$ 190,000	$ 3,000
Less current maturities included in current liabilities		167,355	3,000
Total long term debt			$ 190,000	$ 190,000