Debt instrument covenant minimum liquidity.

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Decrease in excess cash flow.

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Excess cash flow percentage.

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Excess cash flow percentage depending on secured leverage ratio.

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Funds provided to pay interest on debt instrument deposited into escrow account.

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Letter of credit outstanding fronting fee percentage.

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Letter of credit participation fee percentage.

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Maximum permitted leverage ratio.

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Minimum fixed charge coverage ratio.

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Secured leverage ratio.

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Senior unsecured notes interest payment maturity date.

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Senior unsecured notes indenture date.

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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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Percentage of voting equity interests acquired at the acquisition date in the business combination.

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Carrying amount as of the balance sheet date of cash collateral held for borrowed securities, for which the cash is restricted as to withdrawal or usage.

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The number of new shares issued in the conversion of stock in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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The average effective interest rate during the reporting period.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Amount of the required periodic payments including both interest and principal payments.

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying amount of collateralized debt obligations with maturities initially due after one year or beyond the operating cycle, if longer, excluding the current portion. Obligations include, but not limited to, mortgage loans, chattel loans, and other borrowings secured by assets.

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Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

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Description of the reverse stock split arrangement. Also provide the retroactive effect given by the reverse split that occurs after the balance sheet date but before the release of financial statements.

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Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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Business Combination Agreement with Chicago Bridge & Iron Company N.V. ("CB&I") - Additional Information (Detail)			3 Months Ended
	Apr. 18, 2018 USD ($)	Dec. 18, 2017 USD ($) shares	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Business combination, ownership percentage		53.00%
Term facility outstanding Amount			$ 537,258,000	$ 536,977,000
Minimum fixed charge coverage ratio	1.50%
Other operating (income) expenses [Member] \| Chicago Bridge & Iron Company N.V. [Member]
Business Acquisition [Line Items]
Business combinaton, associated cost			$ 11,000,000
Subsequent Event [Member]
Business Acquisition [Line Items]
Excess cash flow	75.00%
Decrease in excess cash flow	50.00%
Excess cash flow percentage depending on secured leverage ratio	25.00%
Repayment of term loan	$ 6,000,000
Commitment fee on the unused portion of credit agreement	0.50%
Letter of credit outstanding fronting fee percentage	0.25%
Debt instrument covenant minimum liquidity	$ 200,000,000
Subsequent Event [Member] \| Federal Funds Rate [Member]
Business Acquisition [Line Items]
Base rate and applicable margin	0.50%
Subsequent Event [Member] \| 30-day Eurodollar Rate [Member]
Business Acquisition [Line Items]
Base rate and applicable margin	1.00%
10.625% Senior Unsecured Notes Due 2024 [Member] \| Subsequent Event [Member]
Business Acquisition [Line Items]
Redemption price percentage	100.00%
10.625% Senior Unsecured Notes Due 2024 [Member] \| Subsequent Event [Member] \| Mc Dermott Escrow One Incorporation And Mc Dermott Escrow Two Incorporation
Business Acquisition [Line Items]
Senior unsecured long-term borrowing	$ 1,300,000,000
Debt instrument interest rate	10.625%
Debt instrument maturity date	May 01, 2024
10.625% Senior Unsecured Notes Due 2024 [Member] \| Subsequent Event [Member] \| Escrow Agent [Member]
Business Acquisition [Line Items]
Senior unsecured notes indenture date	Apr. 18, 2018
Interest payment, maturity date	Jun. 29, 2018
Funds provided to pay interest on debt instrument deposited into segregated escrow account	$ 28,000,000
Maximum [Member] \| Subsequent Event [Member] \| Financial Letters of Credit [Member]
Business Acquisition [Line Items]
Letter of credit participation fee percentage	4.25%
Maximum [Member] \| Subsequent Event [Member] \| Performance Stand By Letters Of Credit [Member]
Business Acquisition [Line Items]
Letter of credit participation fee percentage	2.125%
Maximum [Member] \| Subsequent Event [Member] \| Eurodollar Rate [Member]
Business Acquisition [Line Items]
Base rate and applicable margin	4.25%
Maximum [Member] \| Subsequent Event [Member] \| Base Rate [Member]
Business Acquisition [Line Items]
Base rate and applicable margin	3.25%
Minimum [Member] \| Subsequent Event [Member] \| Financial Letters of Credit [Member]
Business Acquisition [Line Items]
Letter of credit participation fee percentage	3.75%
Minimum [Member] \| Subsequent Event [Member] \| Performance Stand By Letters Of Credit [Member]
Business Acquisition [Line Items]
Letter of credit participation fee percentage	1.875%
Minimum [Member] \| Subsequent Event [Member] \| Eurodollar Rate [Member]
Business Acquisition [Line Items]
Base rate and applicable margin	3.75%
Minimum [Member] \| Subsequent Event [Member] \| Base Rate [Member]
Business Acquisition [Line Items]
Base rate and applicable margin	2.75%
Minimum [Member] \| 10.625% Senior Unsecured Notes Due 2024 [Member] \| Subsequent Event [Member]
Business Acquisition [Line Items]
Term facility outstanding Amount	$ 350,000,000
Secured leverage ratio	100.00%
Term Facility [Member]
Business Acquisition [Line Items]
Senior secured long-term borrowing		$ 2,260,000,000
Term Facility [Member] \| Subsequent Event [Member] \| Eurodollar Rate [Member]
Business Acquisition [Line Items]
Base rate and applicable margin	5.00%
Term Facility [Member] \| Subsequent Event [Member] \| Base Rate [Member]
Business Acquisition [Line Items]
Base rate and applicable margin	4.00%
Term Facility [Member] \| Subsequent Event [Member] \| Floor Rate [Member]
Business Acquisition [Line Items]
Base rate and applicable margin	1.00%
Senior Secured Credit Facility
Business Acquisition [Line Items]
Deposited cash collateral account to secure reimbursement obligations		319,000,000
Senior Secured Credit Facility \| Maximum [Member]
Business Acquisition [Line Items]
Senior secured long-term borrowing		310,000,000
Revolving Facility [Member]
Business Acquisition [Line Items]
Senior secured long-term borrowing		1,000,000,000
Letter of Credit Facility [Member]
Business Acquisition [Line Items]
Senior secured long-term borrowing		$ 1,390,000,000
Fiscal Quarter Ending on or Before September 30, 2019 [Member] \| Subsequent Event [Member]
Business Acquisition [Line Items]
Maximum permitted leverage ratio	4.25%
Fiscal Quarter Ending December 31, 2019 [Member] \| Subsequent Event [Member]
Business Acquisition [Line Items]
Maximum permitted leverage ratio	4.00%
Fiscal Quarter Ending After December 31, 2019 and on or Before December 31, 2020 [Member] \| Subsequent Event [Member]
Business Acquisition [Line Items]
Maximum permitted leverage ratio	3.75%
Fiscal Quarter Ending After December 31, 2020 and on or Before December 31, 2021 [Member] \| Subsequent Event [Member]
Business Acquisition [Line Items]
Maximum permitted leverage ratio	3.50%
Fiscal Quarter Ending after December 31, 2021 [Member] \| Subsequent Event [Member]
Business Acquisition [Line Items]
Maximum permitted leverage ratio	3.25%
Chicago Bridge & Iron Company N.V. [Member]
Business Acquisition [Line Items]
Business combination, ownership percentage		47.00%
Business combination, number of McDermott's shares entitled for each share of CB&I owned \| shares		2.47221
Chicago Bridge & Iron Company N.V. [Member] \| Effect of Reverse Stock Split [Member]
Business Acquisition [Line Items]
Business combination, number of McDermott's shares entitled for each share of CB&I owned \| shares		0.82407
Reverse stock split		three-to-one
Reverse stock split, conversion ratio		3