CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 1,906	$ 2,063
Costs and Expenses:
Cost of operations	1,853	1,928
Project intangibles and inventory-related amortization	3	5
Total cost of operations	1,856	1,933
Selling, general and administrative expenses	62	68
Research and development expenses	2	2
Transaction costs	35	4
Restructuring and integration costs	14	69
Other intangibles amortization	8	11
Property, plant and equipment impairment	884
Goodwill impairment	91
Intangible assets impairment	3
Total expenses	2,955	2,087
Loss from investments in unconsolidated affiliates	(2)
Investment in unconsolidated affiliates-related amortization		(1)
Operating loss from continuing operations	(1,051)	(25)
Other expense:
Interest expense, net	(56)	(92)
Reorganization items, net	(246)
Other non-operating income, net	3	1
Total other expense, net	(299)	(91)
Loss from continuing operations before provision for income taxes	(1,350)	(116)
Income tax expense (benefit)	8	(21)
Net loss from continuing operations	(1,358)	(95)
Net (loss) income from discontinued operations	(14)	38
Net loss	(1,372)	(57)
Less: Net income (loss) attributable to noncontrolling interests	6	(1)
Net loss attributable to McDermott	(1,378)	(56)
Dividends on redeemable preferred stock	(3)	(10)
Accretion of redeemable preferred stock	(1)	(4)
Net loss attributable to common stockholders	$ (1,382)	$ (70)
Continuing operations
Basic	$ (7.09)	$ (0.60)
Diluted	(7.09)	(0.60)
Discontinued operations
Basic	(0.07)	0.21
Diluted	$ (0.07)	$ 0.21
Shares used in the computation of net (loss) income per share
Basic	193	181
Diluted	193	181