Oil and Gas Properties - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Property, Plant, and Equipment Disclosure [Line Items]
Oil and gas properties, impairment Loss	$ 1,046	$ 331	$ 1,527	$ 2,934