Summary of Significant Accounting Policies - Summary for Concentration of Receivables, Net of Allowances, By Product or Service (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Major Customer [Line Items]
Concentration of receivables, net of allowances	$ 119,332	$ 77,609	$ 44,423
Product Concentration Risk [Member] | Oil and Natural Gas and Related Products and Services [Member]
Revenue, Major Customer [Line Items]
Concentration of receivables, net of allowances	94,107	52,908
Product Concentration Risk [Member] | Joint Interest Owners [Member]
Revenue, Major Customer [Line Items]
Concentration of receivables, net of allowances	24,830	23,154
Product Concentration Risk [Member] | Derivatives [Member]
Revenue, Major Customer [Line Items]
Concentration of receivables, net of allowances	372	1,528
Product Concentration Risk [Member] | Other [Member]
Revenue, Major Customer [Line Items]
Concentration of receivables, net of allowances	$ 23	$ 19