CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenues	[1]	$ 1,735	$ 789	$ 2,343	$ 1,308
Costs and Expenses:
Cost of operations		1,486	650	1,962	1,079
Project related intangibles amortization		12		12
Total cost of operations		1,498	650	1,974	1,079
Research and development expenses		5	1	5	1
Selling, general and administrative expenses		75	50	124	87
Other intangibles amortization		10		10
Transaction costs		37		40
Restructuring and integration costs		63		75
Other operating expenses (income), net		1		1	(2)
Total expenses		1,689	701	2,229	1,165
Income (loss) from investments in unconsolidated affiliates		3	(3)	(1)	(6)
Operating income		49	85	113	137
Other expense:
Interest expense, net		(72)	(22)	(83)	(39)
Other non-operating expense, net		(16)	(3)	(14)	(2)
Total other expense, net		(88)	(25)	(97)	(41)
(Loss) income before provision for income taxes		(39)	60	16	96
Income tax (benefit) expense		(84)	23	(63)	34
Non-operating loss from investments in unconsolidated affiliates			(1)		(2)
Net income		45	36	79	60
Less: Net (loss) income attributable to noncontrolling interests		(2)		(3)	2
Net income attributable to McDermott		$ 47	$ 36	$ 82	$ 58
Net income per share attributable to McDermott
Basic		$ 0.33	$ 0.38	$ 0.68	$ 0.67
Diluted		$ 0.33	$ 0.38	$ 0.68	$ 0.62
Shares used in the computation of net income per share:
Basic		144	94	120	87
Diluted		144	94	120	94

[1] Intercompany transactions were not significant for the three and six months ended June 30, 2018 and 2017, respectively.