CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net (loss) income	$ (57)	$ 34
Other comprehensive (loss) income, net of tax:
(Loss) gain on derivatives	(19)
Foreign currency translation	(39)	(1)
Total comprehensive (loss) income	(115)	33
Less: Comprehensive loss attributable to noncontrolling interests	(1)	(1)
Comprehensive (loss) income attributable to McDermott	$ (114)	$ 34