Joint Venture and Consortium Arrangements - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($) Train LNG
Chevron-Lummus Global [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	50.00%
NET Power [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	33.30%
Cash commitment	$ 57
NET Power [Member] | McDermott [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Cumulative investments	$ 47
McDermott/CTCI [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	50.00%
io Oil and Gas [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	50.00%
Qingdao McDermott Wuchuan Offshore Engineering Company Ltd. [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	50.00%
Accrued Liabilities [Member] | McDermott/CTCI [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Advances to ventures	$ 95
Accrued Liabilities [Member] | Proportionately Consolidated Joint Ventures [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Advances to ventures	$ 49
CTCI [Member] | McDermott/CTCI [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	50.00%
Exelon [Member] | NET Power [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	33.30%
8 Rivers Capital [Member] | NET Power [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	33.30%
Baker Hughes [Member] | io Oil and Gas [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	50.00%
Wuhan Wuchuan Investment Holding Co., Ltd. [Member] | Qingdao McDermott Wuchuan Offshore Engineering Company Ltd. [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage	50.00%
McDermott/Orano [Member] | McDermott [Member] | Variable Interest Entities ("VIEs") [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentange in consolidated joint ventures	52.00%
McDermott/Orano [Member] | Orano [Member] | Variable Interest Entities ("VIEs") [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentange in consolidated joint ventures	48.00%
McDermott/Zachry [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by parent	50.00%
Number of liquefied natural gas trains | Train	2
McDermott/Zachry [Member] | Zachry [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by noncontrolling owners	50.00%
McDermott/Zachry/Chiyoda [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by parent	33.30%
McDermott/Zachry/Chiyoda [Member] | Zachry [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by noncontrolling owners	33.30%
McDermott/Zachry/Chiyoda [Member] | Chiyoda [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by noncontrolling owners	33.30%
McDermott/Chiyoda [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by parent	50.00%
Number of Liquefied Natural Gas | LNG	3
McDermott/Chiyoda [Member] | Chiyoda [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by noncontrolling owners	50.00%
McDermott/CTCI [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by parent	42.50%
McDermott/CTCI [Member] | CTCI [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by noncontrolling owners	57.50%