Number of equal vesting installments.

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Performance share awards percentage.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Description of service or performance condition required to be met for earning right to award under share-based payment arrangement. Includes, but is not limited to, combination of market, performance or service condition.

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Description of terms of share-based payment arrangement. Includes, but is not limited to, type of award or grantee and reason for issuance.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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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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Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Gross number of share options (or share units) granted during the period.

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No definition available.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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No definition available.

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Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Millions		3 Months Ended
	Feb. 25, 2020 Installment $ / shares shares	Mar. 31, 2020 USD ($) shares	Mar. 31, 2019 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted	1,650,262
Stock options fair value \| $ / shares	$ 5.83
Stock options exercise price \| $ / shares	$ 20.23
Income tax benefit recognized \| $		$ 0	$ 4
Restricted Stock and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	2,535,174
Restricted stock granted fair value \| $ / shares	$ 20.23
Number of equal annual vesting installments \| Installment	3
Duration of performance-based restricted stock awards, vested		The restricted stock and restricted stock units vest in three equal annual installments commencing on the first anniversary of the grant date.
Performance-base restricted stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of performance goal		The 2020 performance share awards can be earned based on performance against two established goals over a three-year performance period.
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
TSR Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of performance goal		The performance share awards are divided into two independent parts that are subject to two separate performance metrics: 85% with a TSR (total shareholder return) goal and 15% with an internal NVA (“National Oilwell Varco Value Added”) (return on capital metric) goal. Performance against the TSR goal is determined by comparing the performance of the Company’s TSR with the TSR performance of the members of the OSX index for the three-year performance period. The TSR portion of the performance share awards is subject to vesting cap equal to 100% of Target Level if the Company’s absolute TSR is negative, regardless of relative TSR results. Conversely, if the Company’s absolute TSR is greater than 15% annualized over the three-year performance period the payout amount shall not be less than 50% of Target Level, regardless of relative TSR results. The NVA goal is based on the Company’s improvement in NVA from the beginning of the performance period until the end of the performance period. NVA shall be calculated as an amount equal to the Company’s (a) gross cash earnings less (b) average gross operating assets times an amount equal to a required return on assets.
TSR [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of performance shares awarded		85.00%
NVA [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of performance shares awarded		15.00%
Minimum [Member] \| Senior Management Employees [Member] \| Performance-base restricted stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0
Maximum [Member] \| Senior Management Employees [Member] \| Performance-base restricted stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	1,063,274
2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares under stock based compensation		20,200,000
Remaining shares available for future grants under the Plan		1,348,877
Stock-based compensation expense \| $		$ 27	$ 33