Summary of Significant Accounting Policies - Property, Plant and Equipment (Details) - Jack Up Rigs $ in Millions	3 Months Ended
Mar. 31, 2018 USD ($)
Minimum
Property, Plant and Equipment
Estimated loss on sale	$ 50
Maximum
Property, Plant and Equipment
Estimated loss on sale	$ 70

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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