Discontinued Operations - Results of Discontinued Operations in our Statement of Operations (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Oct. 21, 2019
Superpriority Credit Agreement [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Re measurement of embedded derivative liability		$ 37		$ 28	$ 60
Lummus Technology [Member] | Disposed of by Sale [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Interest expense, net	[1]	26	$ 1
Lummus Technology [Member] | Disposed of by Sale [Member] | DIP Credit Agreement [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Interest expense, net		26
Lummus Technology [Member] | Disposed of by Sale [Member] | Superpriority Credit Agreement [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Non-cash charge included in interest expense		11
Interest expense related to amortization of discount offset		17
Re measurement of embedded derivative liability		$ 28

[1] ^{Interest expense was allocated to the discontinued operations, due to a requirement to use the proceeds from the sale to repay our debtor-in-possession financing, and included: (1) $26 million of interest expense associated with the DIP Credit Agreement (discussed in Note 11, Debt); (2) an $11 million non-cash charge included in interest expense and associated with the accretion of the make-whole amount owed to the lenders under our Superpriority Credit Agreement, which was rolled up and deemed issued under the DIP Credit Agreement; (3) $17 million of expense related to amortization of the discount offset by a $28 million gain, resulting from the remeasurement of embedded derivative liability, both of which are associated with the indebtedness and other obligations under our Superpriority Credit Agreement, which were rolled up and deemed issued under the DIP Credit Agreement}