Computation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Income (loss) from continuing operations less noncontrolling interests	$ (149,423)	$ 52,739	$ (128,870)	$ 112,000
Income from discontinued operations, net of tax				3,497
Net income (loss) attributable to McDermott International, Inc.	$ (149,423)	$ 52,739	$ (128,870)	$ 115,497
Weighted average common shares (basic)	236,199,438	235,681,213	236,070,311	235,444,733
Effect of dilutive securities:
Stock options, restricted stock and restricted stock units		1,779,552		1,951,964
Adjusted weighted average common shares and assumed exercises of stock options and vesting of stock awards (diluted)	236,199,438	237,460,765	236,070,311	237,396,697
Basic earnings (loss) per share:
Income (loss) from continuing operations less noncontrolling interests	$ (0.63)	$ 0.22	$ (0.55)	$ 0.48
Income from discontinued operations, net of tax				$ 0.01
Net income (loss) attributable to McDermott International, Inc.	$ (0.63)	$ 0.22	$ (0.55)	$ 0.49
Diluted earnings (loss) per share:
Income (loss) from continuing operations less noncontrolling interests	$ (0.63)	$ 0.22	$ (0.55)	$ 0.47
Income from discontinued operations, net of tax				$ 0.01
Net income (loss) attributable to McDermott International, Inc.	$ (0.63)	$ 0.22	$ (0.55)	$ 0.49