CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019		Jun. 30, 2018
Income Statement [Abstract]
Revenues	[1]	$ 2,137	$ 1,735	$ 4,348		$ 2,343
Costs and Expenses:
Cost of operations		1,949	1,486	3,967		1,962
Project intangibles and inventory-related amortization		10	12	20		12
Total cost of operations		1,959	1,498	3,987		1,974
Research and development expenses		8	5	16		5
Selling, general and administrative expenses		77	75	149		124
Other intangibles amortization		22	10	44		10
Transaction costs		11	37	15		40
Restructuring and integration costs		20	63	89		75
Loss on asset disposals		102	1	103		1
Total expenses		2,199	1,689	4,403		2,229
Income (loss) from investments in unconsolidated affiliates		3	3	12		(1)
Investment in unconsolidated affiliates-related amortization		(2)		(5)
Operating (loss) income	[2]	(61)	49	(48)		113
Other expense:
Interest expense, net		(100)	(72)	(192)		(83)
Other non-operating expense, net		(2)	(16)	(1)		(14)
Total other expense, net		(102)	(88)	(193)		(97)
(Loss) income before provision for income taxes		(163)	(39)	(241)		16
Income tax benefit		(49)	(84)	(70)		(63)
Net (loss) income		(114)	45	(171)		79
Less: Net income (loss) attributable to noncontrolling interests		18	(2)	17		(3)
Net (loss) income attributable to McDermott		(132)	47	(188)	[3]	82	[4]
Dividends on redeemable preferred stock		(10)		(20)	[3]
Accretion of redeemable preferred stock		(4)		(8)	[3]
Net (loss) income attributable to common stockholders		$ (146)	$ 47	$ (216)	[3]	$ 82	[4]
Net (loss) income per share attributable to common stockholders
Basic		$ (0.80)	$ 0.33	$ (1.19)	[3]	$ 0.68	[4]
Diluted		$ (0.80)	$ 0.33	$ (1.19)	[3]	$ 0.68	[4]
Shares used in the computation of net (loss) income per share
Basic		182	144	181	[3]	120	[4]
Diluted		182	144	181	[3]	120	[4]

[1] Intercompany amounts have been eliminated in consolidation.

[2] (1)    NCSA operating results for the three and six months ended June 30, 2019 included $101 million loss on the sale of APP, discussed in Note 4, Disposition of Alloy Piping Products, LLC. Corporate operating results for the three and six months ended June 30, 2019 included:   • $20 million and $89 million of restructuring and integration costs, respectively; and   • $11 million and $15 million of transaction costs, respectively. Corporate operating results for the six months ended June 30, 2018 included:   • $63 million and $75 million of restructuring and integration costs, respectively; and   • $37 million and $40 million of transaction costs, respectively. See Note 11, Restructuring and Integration Costs and Transaction Costs, for further discussion.

[3] ^{The effects of stock-based awards, warrants and redeemable preferred stock were not included in the calculation of diluted earnings per share for the three and six months ended June 30, 2019 due to the net loss for the periods.}

[4] ^{Approximately 0.5 million shares underlying outstanding stock-based awards for the three and six months ended June 30, 2018 were excluded from the computation of diluted earnings per share during the periods because the exercise price of those awards was greater than the average market price of our common stock, and the inclusion of such shares would have been antidilutive in each of those periods.}