For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Summary Of Significant Accounting Policies - Major Customers And Concentration Of Credit Risk (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Petrobras
Revenue, Major Customer [Line Items]
Percentage of concentration risk	28.00%	13.00%
BP
Revenue, Major Customer [Line Items]
Percentage of concentration risk	15.00%	19.00%	17.00%
Talos
Revenue, Major Customer [Line Items]
Percentage of concentration risk		10.00%
Shell
Revenue, Major Customer [Line Items]
Percentage of concentration risk			11.00%