Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Number of additional shares authorized for issuance under an established share-based compensation plan.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Net number of share options (or share units) granted during the period.

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Number of share instruments newly issued under a share-based compensation plan.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Number of share options (or share units) exercised during the current period.

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Stock-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended				12 Months Ended
	Feb. 28, 2017	Feb. 29, 2016	Mar. 31, 2015	May 31, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock options, granted					0	0	0
Number of options, exercised					0	0
Total intrinsic value of stock options exercised							$ 300,000
Fair value of shares vested						$ 1,000,000	3,000,000
Tax benefits realized related to RSUs and RSAs					$ 0	$ 0	$ 0
Performance Shares and Performance Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock issued	236,000	518,000	592,000
Unrecognized compensation costs related to awards					$ 7,000,000
Expected weighted-average period for recognition of compensation cost					2 years
2014 McDermott International, Inc. Long-Term Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional shares approved for issuance				6,600,000
2009 McDermott International, Inc. Long-Term Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized for issuance					9,000,000
Options to purchase shares, maximum expiration term					7 years