Summary of Significant Accounting Policies - Summary of Outstanding Commodity Derivatives (Detail) - Natural Gas Price Swap Agreements	9 Months Ended
	Sep. 30, 2015 $ / Mcf MMcf
Derivative [Line Items]
Commodity Derivatives Weighted Average Contract Price	3.20
Commodity Derivatives Contract Volume | MMcf	2,700
Commodity Derivatives Beginning of Remaining Contract Period	Oct. 01, 2015
Commodity Derivatives End of Remaining Contract Period	Jun. 30, 2016