Number of equal vesting installments.

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Performance share awards percentage.

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Share based compensation arrangement by share based payment award performance period.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date.

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General descriptive information regarding an arrangement under which employees and directors receive: (a) awards of equity shares, equity share options, or other equity instruments; or (b) the entity incurs liabilities to them: (1) in amounts based, at least in part, on the price of the entity's shares or other equity instruments; or (2) that require or may require settlement by issuance of the entity's shares. Such an arrangement is usually provided to employees and directors to compensate them, provide performance incentives to them, and to attract or retain their services. May also include pertinent information particular to a plan that is not elsewhere specified in the taxonomy.

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- Definition

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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- Definition

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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- Definition

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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No definition available.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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- Definition

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

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No definition available.

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- Definition

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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- Definition

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. 27, 2019 Installment $ / shares shares	Mar. 31, 2019 USD ($) shares	Mar. 31, 2018 USD ($)	May 11, 2018 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares under stock based compensation		69,400,000
Stock option granted	1,493,576
Stock options granted fair value \| $ / shares	$ 9.06
Stock options exercise price \| $ / shares	$ 28.72
Restricted Stock and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	2,895,086
Restricted stock granted fair value \| $ / shares	$ 28.72
Number of equal annual vesting installments \| Installment	3
Vesting term		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 restricted stock and restricted stock units vest in three equal annual installments commencing on the first anniversary of the grant date.
Performance period		3 years
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 can be earned based on performance against two established goals over a three-year performance period. 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 (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 NVA goal is based on the Company’s improvement in NVA (National Oilwell Varco Value Added) 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	665,740
2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares under stock based compensation				17,800,000
Remaining shares available for future grants under the Plan		8,212,512
Stock-based compensation expense \| $		$ 33	$ 27
Income tax benefit recognized \| $		$ 4	$ 2