Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net loss attributable to McDermott International, Inc.	$ (33,684)	$ (64,070)	$ (94,467)	$ (192,940)
Weighted average common shares (basic)	237,429,394	236,257,920	237,262,044	236,132,847
Effect of dilutive securities:
Stock options, restricted stock and restricted stock units	0	0	0	0
Adjusted weighted average common shares and assumed exercises of stock options and vesting of stock awards (diluted)	237,429,394	236,257,920	237,262,044	236,132,847
Basic loss per share
Net loss attributable to McDermott International, Inc.	$ (0.14)	$ (0.27)	$ (0.40)	$ (0.82)
Diluted earnings loss per share:
Net loss attributable to McDermott International, Inc.	$ (0.14)	$ (0.27)	$ (0.40)	$ (0.82)