Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to McDermott International, Inc.	$ 16,108	$ 3,666	$ 34,593	$ 685
Weighted average common shares (basic)	240,899,888	238,594,178	240,093,169	238,128,962
Effect of dilutive securities:
Tangible equity units	40,896,300	40,896,300	40,896,300	40,896,300
Stock options, restricted stock and restricted stock units	2,111,165	1,306,677	2,143,451
Adjusted weighted average common shares and assumed exercises of stock options and vesting of stock awards (diluted)	283,907,353	280,797,155	283,132,920	279,025,262
Net income attributable to McDermott International, Inc.
Basic:	$ 0.07	$ 0.02	$ 0.14
Diluted:	$ 0.06	$ 0.01	$ 0.12