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, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Income (loss) from continuing operations less noncontrolling interests	$ (64,070)	$ 50,612	$ (192,940)	$ 162,612
Income from discontinued operations, net of tax				3,497
Net income (loss) attributable to McDermott International, Inc.	$ (64,070)	$ 50,612	$ (192,940)	$ 166,109
Weighted average common shares (basic)	236,257,920	235,817,203	236,132,847	235,568,889
Effect of dilutive securities:
Stock options, restricted stock and restricted stock units	0	2,049,797	0	1,984,574
Adjusted weighted average common shares and assumed exercises of stock options and vesting of stock awards (diluted)	236,257,920	237,867,000	236,132,847	237,553,463
Basic earnings (loss) per share:
Income (loss) from continuing operations less noncontrolling interests	$ (0.27)	$ 0.21	$ (0.82)	$ 0.69
Income from discontinued operations, net of tax				$ 0.01
Net income (loss) attributable to McDermott International, Inc.	$ (0.27)	$ 0.21	$ (0.82)	$ 0.70
Diluted earnings (loss) per share:
Income (loss) from continuing operations less noncontrolling interests	$ (0.27)	$ 0.21	$ (0.82)	$ 0.68
Income from discontinued operations, net of tax				$ 0.01
Net income (loss) attributable to McDermott International, Inc.	$ (0.27)	$ 0.21	$ (0.82)	$ 0.69