Fair Value Measurements - Additional Information (Detail) $ in Millions	3 Months Ended
Sep. 30, 2019 USD ($) SupportSystem	Dec. 31, 2018 USD ($)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Aggregate carrying value of assets	$ 8,754	$ 9,440
Marine Assets [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Number of offshore diving operations saturation support systems \| SupportSystem	2
Aggregate carrying value of assets	$ 26
Estimated fair value of assets	8
Non-cash impairment charges	$ 18

Number of offshore diving operations saturation support systems.

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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