Quarterly Financial Data (Unaudited) - Selected Unaudited Quarterly Financial Information (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
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 667,418	$ 805,857	$ 1,046,537	$ 550,463	$ 806,400	$ 414,595	$ 476,083	$ 603,811	$ 3,070,275	[1]	$ 2,300,889	[1]	$ 2,658,932	[1]
Operating income (loss)	13,539	29,460	41,632	6,565	25,949	(10,711)	31,525	(38,209)	91,196		8,554		(456,745)
Net Income (loss)	(18,015)	7,534	13,690	(12,048)	12,234	(25,946)	(5,698)	(45,984)	(8,839)		(65,394)		(489,910)
Net income attributable to non-controlling interest	653	3,868	2,164	2,459	4,059	4,306	1,699	536	9,144		10,600		18,958
Net income (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)
Income (loss) per share
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)

[1] Intercompany transactions were not significant during 2015, 2014 and 2013.