Basis of Presentation - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Concentration Risk [Line Items]
Goodwill	$ 111,145		$ 111,145		$ 0
Crude Oil Inventory	$ 3,314		3,314		$ 0
Accrued capital expenditures			$ 106,000	$ 54,500
Noble Energy \| Revenue
Concentration Risk [Line Items]
Concentration risk	55.00%	94.00%	60.00%	97.00%

Future cash outflow to pay for purchases of fixed assets that have occurred.

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