Lease Obligations - Additional Information (Detail) - USD ($) $ in Millions	Jul. 27, 2018	Dec. 31, 2018
Jack Up Barge [Member]
Capital Leased Assets [Line Items]
Property, plant and equipment, net		$ 17.0
Accumulated amortization,net		0.4
Capital lease liability		74.0
Amazon Pipe-lay and Construction Vessel [Member]
Capital Leased Assets [Line Items]
Capital expenditure expected	$ 58.0
Property, plant and equipment, net		52.0
Accumulated amortization,net		3.0
Capital lease liability		$ 53.0
Amazon Pipe-lay and Construction Vessel [Member] \| Minimum [Member]
Capital Leased Assets [Line Items]
Cost of modification including project management and other fees and expenses	260.0
Amazon Pipe-lay and Construction Vessel [Member] \| Maximum [Member]
Capital Leased Assets [Line Items]
Cost of modification including project management and other fees and expenses	$ 290.0

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Capital lease obligations including property plant and equipment net.

+ References

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Cost of modification including fees and expenses.

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- Definition

Present value of minimum lease payments for capital leases net of executory costs, including amounts paid by the lessee to the lessor for insurance, maintenance and taxes.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737

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- Definition

The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 2)
-URI http://asc.fasb.org/extlink&oid=82846649&loc=d3e38371-112697

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-Section 45
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