Risk Management and Derivative Instruments - Open Commodity Positions (Detail)	3 Months Ended
	Mar. 31, 2019 MMBTU $ / MMBTU $ / bbl bbl
Natural Gas Derivative Contracts Fixed Price Swap 2021 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	0
Weighted-average fixed price | $ / MMBTU	0
Natural Gas Derivative Collar Contracts 2021 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	87,500
Weighted-average floor price	2.66
Weighted-average ceiling price	2.99
Crude Oil Derivative Contracts Fixed Price Swap 2021 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	33,750
Weighted-average fixed price	55.93
Crude Oil Derivative Collar Contracts 2021 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	0
Weighted-average floor price	0
Weighted-average ceiling price	0
NGL Derivative Contracts Fixed Price Swap 2021 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	5,500
Weighted-average fixed price	27.23
Crude Oil Derivative Purchased Put Option 2021 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	0
Weighted-average strike price	0
Weighted-average deferred premium	0
Natural Gas Derivative Contracts Fixed Price Swap 2020 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	150,000
Weighted-average fixed price | $ / MMBTU	2.65
Natural Gas Derivative Collar Contracts 2020 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	520,000
Weighted-average floor price	2.64
Weighted-average ceiling price	2.96
Crude Oil Derivative Contracts Fixed Price Swap 2020 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	75,000
Weighted-average fixed price	56.33
Crude Oil Derivative Collar Contracts 2020 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	14,300
Weighted-average floor price	55.00
Weighted-average ceiling price	62.10
NGL Derivative Contracts Fixed Price Swap 2020 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	37,925
Weighted-average fixed price	27.94
Crude Oil Derivative Purchased Put Option 2020 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	25,550
Weighted-average strike price	55.00
Weighted-average deferred premium	7.09
Natural Gas Derivative Contracts Fixed Price Swap Remaining 2019 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	1,540,000
Weighted-average fixed price | $ / MMBTU	2.88
Natural Gas Derivative Collar Contracts Remaining 2019 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	0
Weighted-average floor price	0
Weighted-average ceiling price	0
Crude Oil Derivative Contracts Fixed Price Swap Remaining 2019 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	135,333
Weighted-average fixed price	52.60
Crude Oil Derivative Collar Contracts Remaining 2019 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	50,667
Weighted-average floor price	55.00
Weighted-average ceiling price	63.85
NGL Derivative Contracts Fixed Price Swap Remaining 2019 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	72,000
Weighted-average fixed price	29.96
Crude Oil Derivative Purchased Put Option Remaining 2019 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	0
Weighted-average strike price	0
Weighted-average deferred premium	0