Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Summary of reconciliation of the ARO
Balance at beginning of period			$ 2,321	$ 2,149
Accretion expense	36	24	103	76
Additions assumed with consolidated partnerships			34
Additions during period			164	55
Balance at end of period	$ 2,622	$ 2,280	$ 2,622	$ 2,280