Acquisitions (Schedule of Pro Forma Results) (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
3 Months Ended 6 Months Ended
Feb. 28, 2014
Feb. 28, 2013
Feb. 28, 2014
Feb. 28, 2013
Acquisitions [Abstract]        
Oil and Gas Revenues $ 23,028 $ 13,043 $ 44,659 $ 24,004
Net income $ 5,161 $ 3,573 $ 12,091 $ 6,820
Earnings per common share        
Basic $ 0.07 $ 0.06 $ 0.16 $ 0.13
Diluted $ 0.07 $ 0.06 $ 0.16 $ 0.12