Commodity Derivative Positions (Detail) $ in Thousands	3 Months Ended
Mar. 31, 2017 USD ($) bbl $ / bbl	Dec. 31, 2016 USD ($)
Derivative Instruments Related to Oil and Gas Production [Line Items]
Derivative Liability	$ 8,361	$ 27,369
Settlement Agreement [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Fair Value Asset	0
Fair Value Liability	$ 142
Crude Oil \| Second Quarter 2017 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	4,408
Derivative, Swap Type, Average Fixed Price \| $ / bbl	48.62
Fair Value Asset	$ 0
Fair Value Liability	$ 1,003
Crude Oil \| Third Quarter 2017 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	4,408
Derivative, Swap Type, Average Fixed Price \| $ / bbl	48.62
Fair Value Asset	$ 0
Fair Value Liability	$ 1,286
Crude Oil \| Fourth Quarter 2017 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	4,408
Derivative, Swap Type, Average Fixed Price \| $ / bbl	48.62
Fair Value Asset	$ 0
Fair Value Liability	$ 1,355
Crude Oil \| First Quarter 2018 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	3,476
Derivative, Swap Type, Average Fixed Price \| $ / bbl	49.12
Fair Value Asset	$ 0
Fair Value Liability	$ 881
Crude Oil \| Second Quarter 2018 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	3,476
Derivative, Swap Type, Average Fixed Price \| $ / bbl	49.12
Fair Value Asset	$ 0
Fair Value Liability	$ 838
Crude Oil \| Third Quarter 2018 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	3,476
Derivative, Swap Type, Average Fixed Price \| $ / bbl	49.12
Fair Value Asset	$ 0
Fair Value Liability	$ 780
Crude Oil \| Fourth Quarter 2018 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	3,476
Derivative, Swap Type, Average Fixed Price \| $ / bbl	49.12
Fair Value Asset	$ 0
Fair Value Liability	$ 718
Crude Oil \| First Quarter 2019 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	2,916
Derivative, Swap Type, Average Fixed Price \| $ / bbl	49.90
Fair Value Asset	$ 0
Fair Value Liability	$ 359
Crude Oil \| Second Quarter 2019 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	2,916
Derivative, Swap Type, Average Fixed Price \| $ / bbl	49.90
Fair Value Asset	$ 0
Fair Value Liability	$ 338
Crude Oil \| Third Quarter 2019 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	2,916
Derivative, Swap Type, Average Fixed Price \| $ / bbl	49.90
Fair Value Asset	$ 0
Fair Value Liability	$ 329
Crude Oil \| Fourth Quarter 2019 [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Instrument	Swaps
Notional Volume, per day \| bbl	2,916
Derivative, Swap Type, Average Fixed Price \| $ / bbl	49.90
Fair Value Asset	$ 0
Fair Value Liability	$ 332

Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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Description of the type of derivative instrument, such as a swap, forward, and option. Excludes the underlying risk of the instrument.

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