Acquisitions (Narrative) (Details) - LLOG Exploration Offshore L.L.C. and LLOG Bluewater Holdings, L.L.C. $ in Millions	1 Months Ended
Jun. 30, 2019 USD ($)	May 31, 2019 MMBoe
Business Acquisition [Line Items]
Proved reserves \| MMBoe		67
Cash consideration paid to LLOG	$ 1,236.2
Sales Thresholds 2019 to 2022
Business Acquisition [Line Items]
Contingent consideration, maximum	200.0
First Oil from Development Projects
Business Acquisition [Line Items]
Contingent consideration, maximum	$ 50.0

Energy measure of interests in proved developed reserves of crude oil, including condensate and natural gas liquids, natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Form 20-F
-Section Item 18
-Subsection Instruction 2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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