Oil and Gas Properties - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Property, Plant, and Equipment Disclosure [Line Items]
Oil and gas properties, impairment Loss	$ 149	$ 1,301	$ 481	$ 2,604