Derivative Instruments - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) counterparty	Dec. 31, 2014 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Derivative assets | $	$ 97,956	$ 164,878
7.25% Senior Notes due 2019
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Annual interest rate	7.25%
Commodity contracts
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Derivative assets | $	$ 98,000
Number Of Derivative Counterparty | counterparty	7
Commodity contracts | Credit Concentration Risk
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Number Of Derivative Counterparty | counterparty	5
Commodity contracts | Natural Gas
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Third-party quoted forward prices	NYMEX Henry Hub gas
Commodity contracts | Crude Oil
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Third-party quoted forward prices	West Texas Intermediate crude oil