Joint Venture and Consortium Arrangements - Additional Information (Detail) $ in Millions				3 Months Ended	9 Months Ended
	Mar. 02, 2020 USD ($)	Mar. 08, 2019 USD ($)	Nov. 08, 2018 USD ($)	Mar. 31, 2020 USD ($) Train LNG	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage				6.00%
NET Power [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage				32.20%
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		$ 95
Accrued Liabilities [Member] | Proportionately Consolidated Joint Ventures [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Advances to ventures				$ 20		$ 29
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				32.20%
8 Rivers Capital [Member] | NET Power [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage				29.30%
Oxy Low Carbon Ventures Limited Liability Corporation | NET Power [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Equity method investment, percentage		6.30%	10.00%	6.30%
Equity method investment, amount sold			$ 60
Cash payment on equity method investment	$ 5	$ 20			$ 11
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 percentage in consolidated joint ventures				70.00%
McDermott/Orano [Member] | Orano [Member] | Variable Interest Entities ("VIEs") [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage in consolidated joint ventures				30.00%
Profit sharing percentage transfer to Orano				18.00%
Mc Dermott And Kentz
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Number of liquefied natural gas trains | LNG				3
Mc Dermott And Kentz | McDermott [Member] | Variable Interest Entities ("VIEs") [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage in consolidated joint ventures				65.00%
Mc Dermott And Kentz | Kentz [Member] | Variable Interest Entities ("VIEs") [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage in consolidated joint ventures				35.00%
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%
CCS JV [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by parent				24.983%
Number of liquefied natural gas trains | LNG				2
CCS JV [Member] | Chiyoda [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by noncontrolling owners				0.068%
CCS JV [Member] | Saipem [Member]
Schedule Of Equity Method Investments And Joint Ventures [Line Items]
Ownership percentage by noncontrolling owners				74.949%