Derivative Instruments - Summary of Derivative Instrument Positions for Future Production Periods (Detail)	6 Months Ended
	Jun. 30, 2019 MMBTU $ / MMBTU $ / bbl bbl
Natural Gas Swaps Production Period July 2019 - December 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	90,000
Weighted Average Price | $ / MMBTU	2.84
Natural Gas Swaps Production Period July 2019 - September 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	15,000
Weighted Average Price | $ / MMBTU	2.79
Basis Swaps Production Period July 2019 - October 2019 [Member] | Appalachia [Member] | Dominion Resources, Inc [Member] | Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	12,500
Weighted Average Price ($/MMBtu) | $ / MMBTU	(0.52)
Basis Swaps Production Period April 2020 - October 2020 [Member] | Appalachia [Member] | Dominion Resources, Inc [Member] | Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	12,500
Weighted Average Price ($/MMBtu) | $ / MMBTU	(0.52)
Basis Swaps Production Period January 2020 - December 2020 [Member] | Appalachia [Member] | Dominion Resources, Inc [Member] | Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	20,000
Weighted Average Price ($/MMBtu) | $ / MMBTU	(0.59)
Basis Swaps Production Period July 2019 - March 2020 [Member] | Appalachia [Member] | Dominion Resources, Inc [Member] | Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	20,000
Weighted Average Price ($/MMBtu) | $ / MMBTU	(0.39)
Basis Swaps Production Period July 2019 - December 2019 [Member] | Appalachia [Member] | Dominion Resources, Inc [Member] | Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	17,500
Weighted Average Price ($/MMBtu) | $ / MMBTU	(0.50)
Natural Gas Collars Production Period July 2019 - September 2019 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	75,000
Weighted Average Price, Floor | $ / MMBTU	2.50
Natural Gas Collars Production Period July 2019 - September 2019 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	75,000
Weighted Average Price, Ceiling | $ / MMBTU	2.87
Natural Gas Collars Production Period October 2019 - December 2019 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	65,000
Weighted Average Price, Floor | $ / MMBTU	2.65
Natural Gas Collars Production Period October 2019 - December 2019 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	65,000
Weighted Average Price, Ceiling | $ / MMBTU	2.96
Natural Gas Three-way Collars Production Period July 2019 - December 2019 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	77,500
Weighted Average Price, Floor | $ / MMBTU	2.72
Natural Gas Three-way Collars Production Period July 2019 - December 2019 [Member] | Put Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	77,500
Weighted Average Price, Floor | $ / MMBTU	2.30
Natural Gas Three-way Collars Production Period July 2019 - December 2019 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	77,500
Weighted Average Price, Ceiling | $ / MMBTU	3.04
Natural Gas Collars Production Period January 2020 - March 2020 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Floor | $ / MMBTU	2.72
Natural Gas Collars Production Period January 2020 - March 2020 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Ceiling | $ / MMBTU	3.15
Natural Gas Three-way Collars Production Period January 2020 - June 2020 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	70,000
Weighted Average Price, Floor | $ / MMBTU	2.70
Natural Gas Three-way Collars Production Period January 2020 - June 2020 [Member] | Put Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	70,000
Weighted Average Price, Floor | $ / MMBTU	2.25
Natural Gas Three-way Collars Production Period January 2020 - June 2020 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	70,000
Weighted Average Price, Ceiling | $ / MMBTU	2.98
Natural Gas Collars Production Period April 2020 - June 2020 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	15,000
Weighted Average Price, Floor | $ / MMBTU	2.50
Natural Gas Collars Production Period April 2020 - June 2020 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	15,000
Weighted Average Price, Ceiling | $ / MMBTU	2.80
Natural Gas Three-way Collars Production Period October 2019 - June 2020 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Floor | $ / MMBTU	2.90
Natural Gas Three-way Collars Production Period October 2019 - June 2020 [Member] | Put Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Floor | $ / MMBTU	2.50
Natural Gas Three-way Collars Production Period October 2019 - June 2020 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Ceiling | $ / MMBTU	3.15
Natural Gas Collars Production Period January 2020 - December 2020 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Floor | $ / MMBTU	2.55
Natural Gas Collars Production Period January 2020 - December 2020 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Ceiling | $ / MMBTU	3.00
Natural Gas Three-way Collars Production Period January 2020 - December 2020 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Floor | $ / MMBTU	2.70
Natural Gas Three-way Collars Production Period January 2020 - December 2020 [Member] | Put Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Floor | $ / MMBTU	2.40
Natural Gas Three-way Collars Production Period January 2020 - December 2020 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	30,000
Weighted Average Price, Ceiling | $ / MMBTU	3.05
Natural Gas Call/Put Options Production Period July 2019 - December 2019 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (MMBtu/d) | MMBTU	40,000
Weighted Average Price | $ / MMBTU	3.44
Oil Swaps Production Period July 2019 - December 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price | $ / bbl	59.18
Volume (Bbls/d) | bbl	1,500
Oil Swaps Production Period January 2020 - December 2020 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price | $ / bbl	58.60
Volume (Bbls/d) | bbl	1,000
Oil Collars Production Period July 2019 - December 2019 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Floor | $ / bbl	51.67
Volume (Bbls/d) | bbl	1,500
Oil Collars Production Period July 2019 - December 2019 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Ceiling | $ / bbl	65.92
Volume (Bbls/d) | bbl	1,500
Oil Collars Production Period January 2020 - December 2020 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Floor | $ / bbl	51.50
Volume (Bbls/d) | bbl	1,000
Oil Collars Production Period January 2020 - December 2020 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Ceiling | $ / bbl	64.25
Volume (Bbls/d) | bbl	1,000
Oil Collars Production Period July 2019 - March 2020 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Floor | $ / bbl	60.00
Volume (Bbls/d) | bbl	500
Oil Collars Production Period July 2019 - March 2020 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Ceiling | $ / bbl	67.00
Volume (Bbls/d) | bbl	500
Oil Three-way Collars Production Period July 2019 - December 2019 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Floor | $ / bbl	50.00
Volume (Bbls/d) | bbl	2,000
Oil Three-way Collars Production Period July 2019 - December 2019 [Member] | Put Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Floor | $ / bbl	40.00
Volume (Bbls/d) | bbl	2,000
Oil Three-way Collars Production Period July 2019 - December 2019 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Ceiling | $ / bbl	60.56
Volume (Bbls/d) | bbl	2,000
Oil Three-way Collars Production Period January 2020 - June 2020 [Member] | Put Option [Member] | Purchase [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Floor | $ / bbl	62.50
Volume (Bbls/d) | bbl	2,000
Oil Three-way Collars Production Period January 2020 - June 2020 [Member] | Put Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Floor | $ / bbl	55.00
Volume (Bbls/d) | bbl	2,000
Oil Three-way Collars Production Period January 2020 - June 2020 [Member] | Call Option [Member] | Sold [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price, Ceiling | $ / bbl	74.00
Volume (Bbls/d) | bbl	2,000
Propane Swaps Production Period July 2019 - December 2019 [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Weighted Average Price | $ / bbl	39.90
Volume (Bbls/d) | bbl	350