Business Combination - Summary of Pro Forma Financial Information (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended	9 Months Ended
		Sep. 30, 2018	Sep. 30, 2018
Business Combinations [Abstract]
Pro forma revenue	[1]	$ 2,289	$ 7,135
Pro forma net income attributable to common stockholders	[1]	$ 33	$ 128
Pro forma net income per share attributable to common stockholders
Basic	[1]	$ 0.18	$ 0.71
Diluted	[1]	$ 0.18	$ 0.71
Shares used in the computation of net income per share
Basic	[1],[2]	180	180
Diluted	[1],[2]	181	181

[1] Adjustments, net of tax, included in the pro forma net income above that were of a non-recurring nature totaled $28 million and $136 million for the three and nine months ended September 30, 2018, respectively. The adjustments reflect the elimination of (1) restructuring and integration costs ($24 million and $90 million for the three and nine months ended September 30, 2018, respectively); and (2) transaction costs ($4 million and $35 million for the three and nine months ended September 30, 2018, respectively) and debt extinguishment costs of $11 million incurred for the three and nine months ended September 30, 2018, that were included in McDermott and CB&I’s historical results for the three and nine months ended September 30, 2018, respectively. These pro forma results exclude the effect of adjustments to the opening balance sheet associated with fair value purchase accounting estimates.

[2] Pro forma net income per share was calculated using weighted average basic shares outstanding during the three months ended September 30, 2018