Commitments and Contingencies - Self Insurance Disclosures (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Self-Insurance disclosures
Employer's liability claims subject to per-occurrence deductible	$ 3.0
Workers automobile claims	2.5
General liability claims subject to per-occurrence deductible	5.0
Deductions in land rigs and for offshore rigs	5.0
Latin American tax authority | Minimum
Income tax
Aggregate remaining amounts assessed or expected to assessed range	3.0
Latin American tax authority | Maximum
Income tax
Aggregate remaining amounts assessed or expected to assessed range	$ 8.0