Acquisition (Preliminary Purchase Price Allocation) (Details) $ in Thousands	1 Months Ended
	Jun. 30, 2019 USD ($) MMBoe	Dec. 31, 2018 USD ($) MMBoe
Business Acquisition [Line Items]
Fair value of net assets contributed		$ 0
Contingent consideration		89,444
NCI in acquired assets		$ 0
Petrobas America Inc
Business Acquisition [Line Items]
Proved Developed Reserves (Energy) | MMBoe		97
Cash consideration paid		$ 788,724
Fair value of net assets contributed		154,469
Contingent consideration		52,540
NCI in acquired assets		248,933
Total purchase consideration		1,244,666
Fair value of Property, plant and equipment		1,627,429
Other assets		5,628
Less: Asset retirement obligations		(388,391)
Total net assets		1,244,666
LLOG Exploration Offshore L.L.C. and LLOG Bluewater Holdings, L.L.C.
Business Acquisition [Line Items]
Proved Developed Reserves (Energy) | MMBoe	67
Cash consideration paid	$ 1,226,261
Total purchase consideration		1,315,705
Fair value of Property, plant and equipment		1,340,206
Other assets		12,771
Less: Asset retirement obligations		(37,272)
Total net assets		$ 1,315,705