Equity-Based Compensation - RSUs and Changes (Detail) - RSUs [Member] shares in Millions	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding as of December 31, 2017 | shares	2
Number of Shares, Granted | shares	3	[1]
Number of Shares, Vested | shares	(2)
Number of Shares, Outstanding as of December 31, 2018 | shares	3
Weighted Average Grant Date Fair Value, Outstanding as of December 31, 2017 | $ / shares	$ 14.27
Weighted-Average Grant Date Fair Value, Granted | $ / shares	20.36	[1]
Weighted-Average Grant Date Fair Value, Vested | $ / shares	16.55
Weighted Average Grant Date Fair Value, Outstanding as of December 31, 2018 | $ / shares	$ 19.39

[1] Includes 2 million of RSUs relating to shares of CB&I’s common stock that were cancelled and converted in connection with the Combination at a weighted-average grant-date fair value per share of $19.92.