Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net loss from continuing operations attributable to McDermott	$ (1,358)	$ (95)
Net (loss) income from discontinued operations attributable to McDermott	(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

Income loss from continuing operation.

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