XML 38 R32.htm IDEA: XBRL DOCUMENT v2.4.0.6
Changes in Asset Retirement Obligations (Detail) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Reconciliation of Changes in Asset Retirement Obligations [Line Items]    
Asset retirement obligations, December 31, 2011 $ 908,790 $ 883,066
Liabilities incurred during the period 347,018 297,800
Liabilities settled during the year (1,427) (359,513)
Accretion 93,973 87,437
Asset retirement obligations, December 31, 2012 $ 1,336,151 $ 908,790