Summary of Accounts Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Receivables [Abstract]
Customers	$ 22,573	$ 23,481
Joint interest partners	12,849	18,381
Other	6,510	7,658
Accounts Receivable, Gross, Current, Total	41,932	49,520
Less: Allowance for doubtful accounts	(1,618)	(1,555)
Accounts receivable, net of allowance for doubtful accounts	$ 40,314	$ 47,965