Goodwill and Other Intangible Assets - Schedule of Project Related Intangibles (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended														12 Months Ended
	Dec. 31, 2019		Sep. 30, 2019	[1]	Jun. 30, 2019	[1]	Mar. 31, 2019	[1]	Dec. 31, 2018	[1],[2]	Sep. 30, 2018	[1],[2]	Jun. 30, 2018	[1],[2]	Dec. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Net amortization expense	$ 22	[1]	$ 21		$ 22		$ 22		$ 27		$ 25		$ 10		$ 87	$ 62
Project Related Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Net amortization expense															34
Impairment charge															3
Net amortization expense, 2020	22														22
Net amortization expense, 2021	5														5
Net amortization expense, 2022	8														8
Net amortization expense, 2023	$ 2														$ 2

[1] Represents amortization of other intangible assets acquired in the Combination. See Note 9, Goodwill and Other Intangible Assets, for further discussion.

[2] Results in the second, third and fourth quarters of 2018 reflect impacts of the Combination from the Combination Date.