XML 20 R32.htm IDEA: XBRL DOCUMENT v2.4.0.6
Asset Retirement Obligation (Details) (USD $)
In Thousands, unless otherwise specified
6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Asset Retirement Obligation [Abstract]    
Asset Retirement Obligation, Beginning Balance $ 1,927  
Accretion expense 67 51
Liabilities incurred 92  
Liabilities settled (41) (66)
Asset Retirement Obligation, Ending Balance $ 2,045