Risk Management and Derivative Instruments - Open Commodity Positions (Detail)	9 Months Ended
	Sep. 30, 2020 MMBTU $ / MMBTU $ / bbl bbl
Natural Gas Derivative Contracts Fixed Price Swap 2022 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	500,000
Weighted-average fixed price | $ / MMBTU	2.45
Natural Gas Derivative Two Way Collars Contracts 2022 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	200,000
Weighted-average floor price	2.10
Weighted-average ceiling price	2.99
Natural Gas P E P L Basis Swaps Two Thousand Twenty Two
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	0
Weighted-average spread | $ / MMBTU	0
Crude Oil Derivative Contracts Fixed Price Swap 2022 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	30,000
Weighted-average fixed price	55.32
Crude Oil Derivative Two Way Collars Contracts 2022 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	0
Weighted-average floor price	0
Weighted-average ceiling price	0
Crude Oil Derivative Three Way Collars Contracts 2022 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	0
Weighted-average floor price	0
Weighted-average ceiling price	0
Weighted-average sub-floor price	0
NGL Derivative Contracts Fixed Price Swap 2022 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	0
Weighted-average fixed price	0
Natural Gas Derivative Contracts Fixed Price Swap 2021 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	925,000
Weighted-average fixed price | $ / MMBTU	2.49
Natural Gas Derivative Two Way Collars Contracts 2021 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	925,000
Weighted-average floor price	2.10
Weighted-average ceiling price	3.28
Natural Gas P E P L Basis Swaps Two Thousand Twenty One
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	500,000
Weighted-average spread | $ / MMBTU	(0.40)
Crude Oil Derivative Contracts Fixed Price Swap 2021 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	53,750
Weighted-average fixed price	52.02
Crude Oil Derivative Two Way Collars Contracts 2021 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	0
Weighted-average floor price	0
Weighted-average ceiling price	0
Crude Oil Derivative Three Way Collars Contracts 2021 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	20,000
Weighted-average floor price	40.00
Weighted-average ceiling price	51.30
Weighted-average sub-floor price	30.00
NGL Derivative Contracts Fixed Price Swap 2021 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	22,800
Weighted-average fixed price	24.25
Natural Gas Derivative Contracts Fixed Price Swap Remaining 2020 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	1,450,000
Weighted-average fixed price | $ / MMBTU	2.26
Natural Gas Derivative Two Way Collars Contracts Remaining 2020 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	420,000
Weighted-average floor price	2.60
Weighted-average ceiling price	2.88
Natural Gas PEPL Basis Swaps Remaining Remaining 2020 [Member]
Derivative [Line Items]
Average monthly volume (MMBtu) | MMBTU	600,000
Weighted-average spread | $ / MMBTU	(0.46)
Crude Oil Derivative Contracts Fixed Price Swap Remaining 2020 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	199,300
Weighted-average fixed price	57.41
Crude Oil Derivative Two Way Collars Contracts Remaining 2020 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	14,300
Weighted-average floor price	55.00
Weighted-average ceiling price	62.10
Crude Oil Derivative Three Way Collars Contracts Remaining 2020 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	30,500
Weighted-average floor price	50.00
Weighted-average ceiling price	65.75
Weighted-average sub-floor price	40.00
NGL Derivative Contracts Fixed Price Swap Remaining 2020 [Member]
Derivative [Line Items]
Average monthly volume (Bbls) | bbl	111,450
Weighted-average fixed price	21.99