Exploration and production activities (Unaudited) (Notes)

12 Months Ended

Dec. 31, 2017

Oil and Gas Exploration and Production Industries Disclosures [Abstract]

Exploration and production activities

Exploration and Production Activities (Unaudited)

In the second quarter of 2015, the Company began the marketing and sale process of Fidelity with an anticipated sale to occur within one year. Between September 2015 and March 2016, the Company entered into purchase and sale agreements to sell substantially all of

Fidelity's oil and natural gas assets. The completion of these sales occurred between October 2015 and April 2016. Prior to the asset sales, Fidelity was significantly involved in the development and production of oil and natural gas resources. Upon the completion of the asset sales, the Company had no remaining proved oil, NGL or natural gas reserves. At the time the Company committed to a plan to sell Fidelity, the Company stopped the use of the full-cost method of accounting for its oil and natural gas production activities. The assets and liabilities were classified as held for sale and the results of operations included in income (loss) from discontinued operations, other than certain general and administrative costs and interest expense which do not meet the criteria for income (loss) from discontinued operations. For more information, see Note 2.