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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income (loss) attributable to McDermott International, Inc.	$ 20,657	$ 11,526	$ 18,485	$ (2,981)
Weighted average common shares (basic)	240,338,540	238,332,012	239,739,204	237,918,366
Effect of dilutive securities:
Tangible equity units	40,896,300	40,896,300	40,896,300
Stock options, restricted stock and restricted stock units	3,674,574	10,461,669	2,496,734	40,900,000
Adjusted weighted average common shares and assumed exercises of stock options and vesting of stock awards (diluted)	284,909,414	289,689,981	283,132,238	237,918,366
Net income (loss) attributable to McDermott International, Inc.
Basic:	$ 0.09	$ 0.05	$ 0.08	$ (0.01)
Diluted:	$ 0.07	$ 0.04	$ 0.07	$ (0.01)