Sale of Oil and Natural Gas Property Interests	12 Months Ended
Dec. 31, 2018
Discontinued Operations And Disposal Groups [Abstract]
Sale of Oil and Natural Gas Property Interests	Note 4—Sale of Oil and Natural Gas Property Interests Asset Sales During the year ended December 31, 2016, the Company completed the sale of its Conventional oil and gas properties and related equipment for approximately $4.7 million. As of December 31, 2015, the Company was actively negotiating the sale of these assets and the costs related to these properties of approximately $21.8 million and corresponding asset retirement obligations of approximately $19.1 million were classified as held for sale in the consolidated balance sheets as of December 31, 2015. As a result of this sale, the Company recognized a gain of approximately $1.1 million. During the year ended December 31, 2016, the Company sold additional pipeline assets, which resulted in proceeds of approximately $0.4 million and a loss of less than $0.1 million. During the year ended December 31, 2016, the Company received $3.9 million from the sale of mineral interests related primarily to unproved properties to a third party. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and gas properties. During the year ended December 31, 2016, the Company received $4.8 million from the sale of unproved leases to a third party. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and gas properties. During the year ended December 31, 2016, the Company received approximately $63.8 million from a completed asset sale with a third party totaling approximately 9,900 acres. As a result of this sale, the Company recognized a loss of approximately $7.6 million. During the year ended December 31, 2017, the Company received approximately $0.5 million from a completed asset sale with a third party totaling approximately 100 acres. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and natural gas properties. During the year ended December 31, 2017, the Company received approximately $0.8 million from a completed asset sale with a third party totaling approximately 150 acres. As a result of this sale, the Company recognized a gain of approximately $0.2 million. During the year ended December 31, 2018, the Company received approximately $6.0 million from a completed asset sale of approximately 1,000 acres to a third party. As a result of this sale, the Company recognized a gain of approximately $1.5 million. During the year ended December 31, 2018, the Company received approximately $3.8 million from a completed asset sale of approximately 400 acres to a third party. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and natural gas properties. During the year ended December 31, 2018, the Company received approximately $0.3 million from a completed asset sale of approximately 50 acres to a third party. As a result of this sale, the Company recognized a gain of approximately $0.3 million. During the year ended December 31, 2018, the Company sold the $0.2 million of pipeline assets. As a result of this sale, the Company recognized a loss of less than approximately $0.1 million. These pipeline assets were classified as held for sale on the consolidated balance sheets as of December 31, 2015. Acreage Trades During the year ended December 31, 2016, the Company received approximately $1.6 million from completed acreage trades with various working interest owners totaling approximately 249.5 acres. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and gas properties.

Sale of Oil and Natural Gas Property Interests

12 Months Ended

Dec. 31, 2018

Discontinued Operations And Disposal Groups [Abstract]

Sale of Oil and Natural Gas Property Interests

Note 4—Sale of Oil and Natural Gas Property Interests

Asset Sales

During the year ended December 31, 2016, the Company completed the sale of its Conventional oil and gas properties and related equipment for approximately $4.7 million. As of December 31, 2015, the Company was actively negotiating the sale of these assets and the costs related to these properties of approximately $21.8 million and corresponding asset retirement obligations of approximately $19.1 million were classified as held for sale in the consolidated balance sheets as of December 31, 2015. As a result of this sale, the Company recognized a gain of approximately $1.1 million.

During the year ended December 31, 2016, the Company sold additional pipeline assets, which resulted in proceeds of approximately $0.4 million and a loss of less than $0.1 million.

During the year ended December 31, 2016, the Company received $3.9 million from the sale of mineral interests related primarily to unproved properties to a third party. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and gas properties.

During the year ended December 31, 2016, the Company received $4.8 million from the sale of unproved leases to a third party. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and gas properties.

During the year ended December 31, 2016, the Company received approximately $63.8 million from a completed asset sale with a third party totaling approximately 9,900 acres. As a result of this sale, the Company recognized a loss of approximately $7.6 million.

During the year ended December 31, 2017, the Company received approximately $0.5 million from a completed asset sale with a third party totaling approximately 100 acres. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and natural gas properties.

During the year ended December 31, 2017, the Company received approximately $0.8 million from a completed asset sale with a third party totaling approximately 150 acres. As a result of this sale, the Company recognized a gain of approximately $0.2 million.

During the year ended December 31, 2018, the Company received approximately $6.0 million from a completed asset sale of approximately 1,000 acres to a third party. As a result of this sale, the Company recognized a gain of approximately $1.5 million.

During the year ended December 31, 2018, the Company received approximately $3.8 million from a completed asset sale of approximately 400 acres to a third party. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and natural gas properties.

During the year ended December 31, 2018, the Company received approximately $0.3 million from a completed asset sale of approximately 50 acres to a third party. As a result of this sale, the Company recognized a gain of approximately $0.3 million.

During the year ended December 31, 2018, the Company sold the $0.2 million of pipeline assets. As a result of this sale, the Company recognized a loss of less than approximately $0.1 million. These pipeline assets were classified as held for sale on the consolidated balance sheets as of December 31, 2015.

Acreage Trades

During the year ended December 31, 2016, the Company received approximately $1.6 million from completed acreage trades with various working interest owners totaling approximately 249.5 acres. No gain or loss was recognized for this transaction, which was recorded as a reduction of oil and gas properties.