Business Combination - Summary of Final Purchase Price Allocation of Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Millions			9 Months Ended
		May 10, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	[1]
Net tangible assets:
Goodwill			$ 1,335		$ 2,654
Total Combination consideration transferred, net of cash acquired		$ 4,100	$ 7	$ 2,374
Chicago Bridge & Iron Company N.V. [Member]
Net tangible assets:
Cash		498
Accounts receivable		791
Inventory		111
Contracts in progress		272
Assets held for sale	[2]	70
Other current assets		272
Investments in unconsolidated affiliates	[3]	426
Property, plant and equipment		396
Other non-current assets		127
Accounts payable		(499)
Advance billings on contracts	[4]	(2,410)
Deferred tax liabilities		(16)
Other current liabilities		(1,237)
Other non-current liabilities		(453)
Noncontrolling interest		14
Total net tangible liabilities		(1,638)
Project-related intangible assets/liabilities, net	[5]	150
Other intangible assets	[6]	1,063
Net identifiable liabilities		(425)
Goodwill	[7]	4,990
Total Combination consideration transferred		4,565
Less: Cash acquired		(498)
Total Combination consideration transferred, net of cash acquired		$ 4,067

[1] As of December 31, 2018, we had approximately $2.2 billion of cumulative impairment charges recorded in conjunction with our impairment assessment performed during the fourth quarter of 2018, as further described in the 2018 Form 10-K

[2] Assets held for sale included CB&I’s former administrative headquarters within Corporate and various fabrication facilities within NCSA. During the third quarter of 2018, we completed the sale of CB&I’s former administrative headquarters for proceeds of $52 million.

[3] Investments in unconsolidated affiliates includes a fair value adjustment of $215 million associated with the Combination. Approximately $146 million of the fair value adjustment is attributable to the basis difference between McDermott’s investment and the underlying equity in identifiable assets of unconsolidated affiliates and will be amortized to Investment in unconsolidated affiliates-related amortization over a range of two to 30 years based on the life of assets to which the basis difference is attributed.

[4] Advance billings on contracts includes accrued provisions for estimated losses on projects of $374 million, primarily associated with the Cameron LNG and Freeport LNG Trains 1 and 2 projects, the now-substantially completed gas power project for a unit of Calpine Corporation (“Calpine”) and the now-completed gas power project for Indianapolis Power & Light Company.

[5] Project-related intangible assets/liabilities, net includes intangible asset and liabilities of $259 million and $109 million, respectively. The balances represent the fair value of acquired remaining performance obligations (“RPOs”) and normalized profit margin fair value associated with acquired long-term contracts that were deemed to be lower than fair value (excluding amounts recorded in Advance billings on contracts and Contracts in progress) as of the Combination Date. The project-related intangible assets and liabilities will be amortized as the applicable projects progress over a range of two to six years within Project-related intangibles amortization in our Statements of Operations.

[6] Other intangible assets are reflected in the table below and recorded at estimated fair value, as determined by our management, based on available information, which includes valuations prepared by external experts. The estimated useful lives for intangible assets were determined based upon the remaining useful economic lives of the intangible assets that are expected to contribute directly or indirectly to future cash flows.

[7] Goodwill resulted from the acquired established workforce, which does not qualify for separate recognition, as well as expected future cost savings and revenue synergies associated with the combined operations. Of the approximately $5 billion of goodwill recorded in conjunction with the Combination, $2.7 billion, $461 million, $50 million, $52 million and $1.7 billion was allocated to our NCSA, EARC, MENA, APAC and Technology reporting segments, respectively. Approximately $1.7 billion of the opening goodwill balance is deductible for tax purposes.