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Pension and Post-retirement Benefits - Additional Information (Detail) - USD ($) $ in Millions	8 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined contribution expense		$ 37	$ 22	$ 5
Health care cost trend rates in 2020		6.25%
Health care cost trend rates projected to decline in 2025		5.00%
Year health care cost trend rates projected to decline		2025
Contributions to multi-employer plans		$ 11
Fixed Income [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target weighted-average asset allocations by asset category		20.00%
Fixed Income [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target weighted-average asset allocations by asset category		25.00%
Equity Securities [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target weighted-average asset allocations by asset category		70.00%
Equity Securities [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target weighted-average asset allocations by asset category		75.00%
Other Investments [Member] \| Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target weighted-average asset allocations by asset category		5.00%
Other Investments [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target weighted-average asset allocations by asset category		10.00%
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for all defined benefit pension plans	$ 1,400	$ 1,500	$ 1,400
CB&I [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution expense	$ 16