Acquisitions - 2016 Activity (Details) - Delaware Basin Interests [Member] $ in Millions	Sep. 01, 2016 USD ($) a	Feb. 28, 2017 a
Business Acquisition [Line Items]
Business Combination, Consideration Transferred \| $	$ 558.5
Oil and Gas Area, Gross	26,797	100,306
Oil and Gas Area, Net	19,262	80,339

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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