Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net loss attributable to McDermott International, Inc.	$ (18,668)	$ 3,666	$ 11,526	$ (14,507)	$ 8,175	$ (30,252)	$ (7,397)	$ (46,520)	$ (17,983)	$ (75,994)	$ (508,868)
Weighted average common shares (basic)									238,240,763	237,229,086	236,514,584
Effect of dilutive securities:
Stock options, restricted stock and restricted stock units									40,900,000	30,700,000
Adjusted weighted average common shares and assumed exercises of stock options and vesting of stock awards (diluted)									238,240,763	237,229,086	236,514,584
Net loss attributable to McDermott International, Inc.
Basic:	$ (0.08)	$ 0.02	$ 0.05	$ (0.06)	$ 0.03	$ (0.13)	$ (0.03)	$ (0.20)	$ (0.08)	$ (0.32)	$ (2.15)
Diluted:	$ (0.08)	$ 0.01	$ 0.04	$ (0.06)	$ 0.03	$ (0.13)	$ (0.03)	$ (0.20)	$ (0.08)	$ (0.32)	$ (2.15)