Commodity Derivative Positions (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) bbl counterparty $ / bbl $ / bbl
Crude Oil
Derivative Instruments Related to Oil and Gas Production [Line Items]
Derivative, Swap Type, Average Fixed Price | $ / bbl	49.12
Settlement Agreement [Member]
Derivative Instruments Related to Oil and Gas Production [Line Items]
Fair Value Liability	$ 818
Fourth Quarter 2019 [Member] | Crude Oil
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	$ 1,414
Third Quarter 2019 [Member] | Crude Oil
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	$ 1,423
Second Quarter 2019 [Member] | Crude Oil
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	$ 1,438
First Quarter 2019 [Member] | Crude Oil
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	$ 1,471
Fourth Quarter 2018 [Member] | Crude Oil
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	$ 2,091
Third Quarter 2018 [Member] | Crude Oil
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	$ 2,140
Second Quarter 2018 [Member] | Crude Oil
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	$ 2,193
First Quarter 2018 [Member] | Crude Oil
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	$ 2,267
Fourth Quarter 2017 [Member] | Crude Oil
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	$ 3,260
Third Quarter 2017 [Member] | Crude Oil
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	$ 3,290
Second Quarter 2017 [Member] | Crude Oil
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	$ 3,110
First Quarter 2017 [Member] | Crude Oil
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	$ 2,454
Commodity contracts
Derivative Instruments Related to Oil and Gas Production [Line Items]
Number Of Derivative Counterparty | counterparty	3