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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income (loss) attributable to McDermott International, Inc.	$ 11,526	$ (7,397)	$ (2,981)	$ (53,917)
Weighted average common shares (basic)	238,332,012	237,395,580	237,918,366	237,178,369
Effect of dilutive securities:
Tangible equity units	40,896,300
Stock options, restricted stock and restricted stock units	10,461,669
Adjusted weighted average common shares and assumed exercises of stock options and vesting of stock awards (diluted)	289,689,981	237,395,580	237,918,366	237,178,369
Basic loss per share
Net income (loss) attributable to McDermott International, Inc.	$ 0.05	$ (0.03)	$ (0.01)	$ (0.23)
Diluted loss per share:
Net income (loss) attributable to McDermott International, Inc.	$ 0.04	$ (0.03)	$ (0.01)	$ (0.23)