Summary of Significant Accounting Policies - Major Customers and Associated Percentage of Revenue (Detail) - Sales Revenue, Net [Member]	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue, Major Customer [Line Items]
Major customers and associated percentage of revenue	85.00%	74.00%	80.00%	77.00%
Customer Concentration Risk [Member] | Antero Resources Corporation [Member]
Revenue, Major Customer [Line Items]
Major customers and associated percentage of revenue	19.00%	48.00%	18.00%	57.00%
Customer Concentration Risk [Member] | ARM Energy Management, LLC [Member]
Revenue, Major Customer [Line Items]
Major customers and associated percentage of revenue	10.00%	26.00%	12.00%	20.00%
Customer Concentration Risk [Member] | Enlink Midstream Operating, L.P. [Member]
Revenue, Major Customer [Line Items]
Major customers and associated percentage of revenue	20.00%		24.00%
Customer Concentration Risk [Member] | Tenaska Marketing Ventures [Member]
Revenue, Major Customer [Line Items]
Major customers and associated percentage of revenue	14.00%		6.00%
Customer Concentration Risk [Member] | Sequent Energy Management, L.P. [Member]
Revenue, Major Customer [Line Items]
Major customers and associated percentage of revenue	22.00%		20.00%