Acquisitions - 2017 Activity (Details) shares in Thousands, $ in Thousands		12 Months Ended
	Feb. 28, 2017 USD ($) a shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 01, 2016 a
Business Acquisition [Line Items]
Common Stock, Conversion Basis		.6442
Shares Held in Escrow | shares		500
Acquisition of leasehold interests		$ 1,370,951	$ 1,960,591	$ 611,280
Additions to midstream assets		$ 204,222	$ 68,139	$ 1,188
Energen Corporation Acquisition [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable | shares		62,800
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable		$ 7,136,037
Delaware Basin Interests [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 1,740,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable | shares	7,690
Shares Held in Escrow | shares	1,150
Oil and Gas Area, Gross | a	100,306				26,797
Oil and Gas Area, Net | a	80,339				19,262
Acquisition of leasehold interests	$ 2,500,000
Additions to midstream assets	$ 47,600
Diamondback Energy, Inc. [Member]
Business Acquisition [Line Items]
acquisition related costs incurred		36,800
Energen [Member]
Business Acquisition [Line Items]
acquisition related costs incurred		$ 59,000