Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Reconciliation of the ARO
Balance at beginning of period			$ 2,149	$ 352
Liabilities transferred due to property disposition
Accretion expense	26	6	52	12
Additions assumed with acquired properties				1,402
Additions during period			10	102
Balance at end of period	$ 2,211	$ 1,868	$ 2,211	$ 1,868