Derivative Instruments - Additional Information (Detail) (USD $)			1 Months Ended							12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Aug. 31, 2011 10.375% Senior Unsecured Notes due 2016	Dec. 31, 2009 10.375% Senior Unsecured Notes due 2016	May 31, 2012 7.25% Senior Unsecured Notes due 2019	Dec. 31, 2013 7.25% Senior Unsecured Notes due 2019	Feb. 29, 2012 7.25% Senior Unsecured Notes due 2019	Dec. 31, 2013 Commodity contracts Entity	Dec. 31, 2013 Commodity contracts Credit Concentration Risk Entity	Dec. 31, 2013 Commodity contracts Natural Gas	Dec. 31, 2013 Commodity contracts Crude Oil
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Third-party quoted forward prices										NYMEX Henry Hub gas	West Texas Intermediate crude oil
Debt hedged by interest rate derivatives				33.33%			33.33%
Annual interest rate				10.375%		7.25%	7.25%
Cash proceeds from termination of interest rate swap			$ 2,900,000		$ 1,200,000
Entered interest rate swap				establish variable rates on approximately one-third of the face amount of the outstanding obligation
Derivative assets	$ 5,382,000	$ 16,473,000						$ 5,400,000
Number of derivative counterparty								5	3