Property Dispositions	12 Months Ended
Dec. 31, 2017
Extractive Industries [Abstract]
Property Acquisitions and Dispositions	Property Dispositions 2017 In September 2017, the Company sold non-strategic properties in the Arkoma Woodford area for cash proceeds of $65.3 million. The sale included approximately 26,000 net acres of leasehold in Atoka, Coal, Hughes, and Pittsburg Counties of Oklahoma and producing properties with production totaling approximately 1,700 barrels of oil equivalent per day. In connection with the transaction, the Company recognized a pre-tax loss of $3.5 million for the year ended December 31, 2017. The disposed properties represented an immaterial portion of the Company’s proved reserves. In September 2017, the Company reached an agreement to sell non-core leasehold in the STACK play in Blaine County, Oklahoma for cash proceeds totaling $63.5 million. A portion of the transaction closed in September 2017, resulting in the receipt of proceeds amounting to $3.6 million and the recognition of a $3.3 million pre-tax gain on sale in the 2017 third quarter. The remainder of the transaction was completed in October 2017 at which time the Company received the remaining $59.9 million of proceeds and recognized an additional pre-tax gain of approximately $53.6 million, which is reflected in fourth quarter 2017 results. The disposed properties represented an immaterial portion of the Company’s production and proved reserves. In September 2017, the Company sold certain oil-loading facilities in Oklahoma for $7.2 million and recognized a $4.2 million pre-tax gain for the year ended December 31, 2017 associated with the transaction. 2016 In October 2016, the Company sold approximately 30,000 net acres of non-strategic leasehold in the SCOOP play in Oklahoma for cash proceeds totaling $295.6 million. The leasehold was located primarily in the eastern portion of the SCOOP play and included producing properties with production totaling approximately 700 barrels of oil equivalent per day. In connection with the transaction, the Company recognized a pre-tax gain of $201.0 million. The disposed properties represented an immaterial portion of the Company’s proved reserves. In September 2016, the Company sold non-strategic properties in North Dakota and Montana for cash proceeds totaling $214.8 million, with no gain or loss recognized. The sale included approximately 68,000 net acres of leasehold primarily in western Williams County, North Dakota, and approximately 12,000 net acres of leasehold in Roosevelt County, Montana. The sale also included producing properties with production totaling approximately 2,700 barrels of oil equivalent per day. The disposed properties represented an immaterial portion of the Company’s proved reserves. In April 2016, the Company sold approximately 132,000 net acres of undeveloped leasehold acreage in Wyoming for cash proceeds totaling $110.0 million. In connection with the transaction, the Company recognized a pre-tax gain of $96.9 million. The disposed properties had no production or proved reserves. 2015 During the year ended December 31, 2015, the Company sold certain non-strategic properties in various areas for cash proceeds totaling $34.0 million. The proceeds primarily related to the disposition of certain non-producing leasehold acreage in Oklahoma for $25.9 million in May 2015. The Company recognized a pre-tax gain on the transaction of $20.5 million. The disposed properties represented an immaterial portion of the Company’s leasehold acreage.

Property Dispositions

2017

In September 2017, the Company sold non-strategic properties in the Arkoma Woodford area for cash proceeds of $65.3 million. The sale included approximately 26,000 net acres of leasehold in Atoka, Coal, Hughes, and Pittsburg Counties of Oklahoma and producing properties with production totaling approximately 1,700 barrels of oil equivalent per day. In connection with the transaction, the Company recognized a pre-tax loss of $3.5 million for the year ended December 31, 2017. The disposed properties represented an immaterial portion of the Company’s proved reserves.

In September 2017, the Company reached an agreement to sell non-core leasehold in the STACK play in Blaine County, Oklahoma for cash proceeds totaling $63.5 million. A portion of the transaction closed in September 2017, resulting in the receipt of proceeds amounting to $3.6 million and the recognition of a $3.3 million pre-tax gain on sale in the 2017 third quarter. The remainder of the transaction was completed in October 2017 at which time the Company received the remaining $59.9 million of proceeds and recognized an additional pre-tax gain of approximately $53.6 million, which is reflected in fourth quarter 2017 results. The disposed properties represented an immaterial portion of the Company’s production and proved reserves.

In September 2017, the Company sold certain oil-loading facilities in Oklahoma for $7.2 million and recognized a $4.2 million pre-tax gain for the year ended December 31, 2017 associated with the transaction.

2016

In October 2016, the Company sold approximately 30,000 net acres of non-strategic leasehold in the SCOOP play in Oklahoma for cash proceeds totaling $295.6 million. The leasehold was located primarily in the eastern portion of the SCOOP play and included producing properties with production totaling approximately 700 barrels of oil equivalent per day. In connection with the transaction, the Company recognized a pre-tax gain of $201.0 million. The disposed properties represented an immaterial portion of the Company’s proved reserves.

In September 2016, the Company sold non-strategic properties in North Dakota and Montana for cash proceeds totaling $214.8 million, with no gain or loss recognized. The sale included approximately 68,000 net acres of leasehold primarily in western Williams County, North Dakota, and approximately 12,000 net acres of leasehold in Roosevelt County, Montana. The sale also included producing properties with production totaling approximately 2,700 barrels of oil equivalent per day. The disposed properties represented an immaterial portion of the Company’s proved reserves.

In April 2016, the Company sold approximately 132,000 net acres of undeveloped leasehold acreage in Wyoming for cash proceeds totaling $110.0 million. In connection with the transaction, the Company recognized a pre-tax gain of $96.9 million. The disposed properties had no production or proved reserves.

2015

During the year ended December 31, 2015, the Company sold certain non-strategic properties in various areas for cash proceeds totaling $34.0 million. The proceeds primarily related to the disposition of certain non-producing leasehold acreage in Oklahoma for $25.9 million in May 2015. The Company recognized a pre-tax gain on the transaction of $20.5 million. The disposed properties represented an immaterial portion of the Company’s leasehold acreage.