Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income attributable to McDermott International, Inc.		$ 36,413	$ 20,657	$ 58,329	$ 18,485
Weighted average common stock (basic)		282,660,314	240,338,540	262,438,822	239,739,204
Effect of dilutive securities:
Tangible equity units	[1]	898,820	40,896,300	19,347,386	40,896,300
Stock options, restricted stock and restricted stock units		1,423,136	3,674,574	2,336,352	2,496,734
Potential dilutive common stock		284,982,270	284,909,414	284,122,560	283,132,238
Net income per share attributable to McDermott International, Inc.
Basic:		$ 0.13	$ 0.09	$ 0.22	$ 0.08
Diluted:		$ 0.13	$ 0.07	$ 0.21	$ 0.07

[1] Represents weighted average TEUs outstanding for the three and six months periods ended June 30, 2017.