CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Revenues	[1]	$ 788,673	$ 706,627	$ 1,308,104	$ 1,435,659
Costs and Expenses:
Cost of operations		650,449	595,343	1,079,039	1,211,345
Research and development expenses		821	99	1,301	130
Selling, general and administrative expenses		50,022	52,075	86,609	90,403
Other operating (income) expenses, net		182	2,122	(2,029)	40,800
Total costs and expenses		701,474	649,639	1,164,920	1,342,678
Operating income		87,199	56,988	143,184	92,981
Other expense:
Interest expense, net		(21,204)	(12,655)	(38,910)	(23,893)
Other non-operating expense, net		(2,491)	(2,851)	(1,877)	(6,242)
Total other expense, net		(23,695)	(15,506)	(40,787)	(30,135)
Income before provision for income taxes		63,504	41,482	102,397	62,846
Provision for income taxes		22,918	19,804	33,689	39,134
Income before income (loss) from Investments in Unconsolidated Affiliates		40,586	21,678	68,708	23,712
Income (loss) from Investments in Unconsolidated Affiliates		(4,127)	127	(8,054)	(4,351)
Net income		36,459	21,805	60,654	19,361
Less: Net income attributable to noncontrolling interest		46	1,148	2,325	876
Net income attributable to McDermott International, Inc.		$ 36,413	$ 20,657	$ 58,329	$ 18,485
Net income per share attributable to McDermott International, Inc.:
Basic		$ 0.13	$ 0.09	$ 0.22	$ 0.08
Diluted		$ 0.13	$ 0.07	$ 0.21	$ 0.07
Shares used in the computation of net income per share:
Basic		282,660,314	240,338,540	262,438,822	239,739,204
Diluted		284,982,270	284,909,414	284,122,560	283,132,238

[1] Intersegment transactions included in revenues were not significant for either of the periods presented.