Oil and Natural Gas Properties - Additional Information (Details) $ in Thousands			3 Months Ended			6 Months Ended	12 Months Ended
	Nov. 21, 2017 well	Feb. 21, 2017 well phase	Mar. 31, 2019 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Business combination, consideration transferred						$ 41,600	$ 149,900
Acquisition-related costs						100	200
Issuance of common units, net of offering costs			$ (43)	$ 8,929	$ 138
East Texas
Business Acquisition [Line Items]
Payments to acquire oil, mineral, and royalty interests						29,200	58,200
2019 Acquisitions
Business Acquisition [Line Items]
Payments to acquire oil, mineral, and royalty interests						28,300
Issuance of common units, net of offering costs						900
2018 Acquisitions
Business Acquisition [Line Items]
Payments to acquire oil, mineral, and royalty interests							57,600
Issuance of common units, net of offering costs							600
Payments to noncontrolling interests							1,700
Angelina County, Texas | Farmout Agreement
Business Acquisition [Line Items]
Business combination, ownership interest, acreage, percent		50.00%
Exploratory wells, expected to be drilled | well		20
Exploratory wells, additional wells to be drilled | well		20
Asset acquisition, number of phases | phase		3
Canaan Resource Partners | Angelina County, Texas | Farmout Agreement
Business Acquisition [Line Items]
Asset acquisition, term of phase		2 years
Asset acquisition, funding requirements, drilling and completion costs, percent		80.00%
Asset acquisition, ownership interest in wells, percent		80.00%
Asset acquisition, ownership interest, gross, percent		40.00%
Asset acquisition, third phase, ownership interest in additional wells, percent		40.00%
Asset acquisition, third phase, ownership interest in additional wells, gross, percent		20.00%
Asset acquisition, third phase, funding requirements, drilling and completion costs, percent		40.00%
Business combination, pro forma information, revenue of acquiree since acquisition date, actual						89,200
Pivotal | San Augustine County, Texas | Farmout Agreement
Business Acquisition [Line Items]
Exploratory wells, expected to be drilled | well	80
Asset acquisition, ownership interest, gross, percent	10.00%
Asset acquisition, ownership interest, in wells operated by others, percent	100.00%
Business combination, pro forma information, revenue of acquiree since acquisition date, actual						102,000
Other long-term liabilities | Canaan Resource Partners | Angelina County, Texas | Farmout Agreement
Business Acquisition [Line Items]
Business combination, pro forma information, working interests in wells drilled and completed, actual						900	11,600
Other long-term liabilities | Pivotal | San Augustine County, Texas | Farmout Agreement
Business Acquisition [Line Items]
Business combination, pro forma information, working interests in wells drilled and completed, actual						$ 75,000	$ 41,200
Minimum | Pivotal | San Augustine County, Texas | Farmout Agreement
Business Acquisition [Line Items]
Asset acquisition, ownership interest, in wells operated by others, gross, percent	12.50%
Maximum | Pivotal | San Augustine County, Texas | Farmout Agreement
Business Acquisition [Line Items]
Asset acquisition, ownership interest, in wells operated by others, gross, percent	25.00%