Oil and Natural Gas Property Transactions - Narrative (Details) shares in Millions, $ in Millions		3 Months Ended				5 Months Ended	9 Months Ended
	Feb. 01, 2019 USD ($) shares	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2018 USD ($) well		Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($) a well
Business Acquisition [Line Items]
Revenues		$ 2,087		$ 2,424	[1]		$ 6,669	$ 7,237	[1]
Proceeds from divestitures of proved and unproved properties							110	395	[2]
Mid-Continent
Business Acquisition [Line Items]
Proceeds from divestitures of proved and unproved properties								$ 491
Number of net acres included in sale | a								238,500
Productive gas wells, number of wells, net | well				3,200				3,200
Other properties
Business Acquisition [Line Items]
Proceeds from divestitures of proved and unproved properties		$ 28	$ 8				$ 110	$ 31
Wildhorse Resource Development Corporation
Business Acquisition [Line Items]
Common stock issued in the merger (in shares) | shares	717.4
Cash	$ 381
Revenues						$ 543
Operating expenses						579
Other expenses						$ 67

[1] Financial information for 2018 has been recast to reflect the retrospective application of the successful efforts method of accounting. See Note 1.

[2] Financial information for 2018 has been recast to reflect the retrospective application of the successful efforts method of accounting. See Note 1.