Debt - Additional Information (Detail) - USD ($)	3 Months Ended
Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Funds available under revolving credit facility	$ 2,000,000,000.0
Interest rate under multi currency facility	LIBOR, NIBOR or CDOR plus 1.25%
Capitalization ratio, Maximum	60.00%
Capitalization ratio, Actual	28.10%
Other debt	$ 130,000,000	$ 129,000,000
Outstanding letters of credit under various bilateral letter of credit facilities	437,000,000
Carrying value of Unsecured Senior Notes	1,584,000,000	1,584,000,000
Unsecured Debt [Member] \| Fair Value, Inputs, Level 2 [Member]
Debt Instrument [Line Items]
Fair value of Unsecured Senior Notes	1,466,000,000	$ 1,610,000,000
Noncontrolling Interests [Member]
Debt Instrument [Line Items]
Other debt	$ 27,000,000
Canadian Dollar Offered Rate (CDOR) [Member]
Debt Instrument [Line Items]
Variable rate	1.25%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility current borrowing capacity	$ 2,000,000,000.0
Funds available under revolving credit facility	1,700,000,000
Credit facility, extendable borrowing capacity	$ 3,000,000,000.0
Variable rate basis	LIBOR, NIBOR or CDOR plus
Outstanding letters of credit issued	$ 0
Foreign Line of Credit [Member]
Debt Instrument [Line Items]
Variable rate	1.40%
Additional line of credit facility borrowing capacity	$ 150,000,000
Debt to equity ratio maximum	75.00%
Borrowings	$ 103,000,000
First payment	$ 5,000,000
Line of credit repayment schedule beginning date	2022-12
Line of credit repayment schedule ending date	2032-06

Additional line of credit facility borrowing capacity.

No definition available.

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Namespace Prefix:	nov_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Interest rate under multicurrency facility.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Line of credit facility covenant compliance debt to capitalization percentage.

+ References

No definition available.

+ Details

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Namespace Prefix:	nov_
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Balance Type:	na
Period Type:	instant

- Definition

Line of credit facility covenant terms maximum debt to capitalization percentage.

+ References

No definition available.

+ Details

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- Definition

Line of credit facility covenant terms maximum debt to equity percentage.

+ References

No definition available.

+ Details

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- Definition

Line of credit facility extended borrowing capacity.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit repayment schedule beginning date.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Line of credit repayment schedule ending date.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Outstanding letters of credit under various bilateral committed letter of credit facilities.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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- Definition

Description of reference rate used for variable rate of debt instrument.

+ References

No definition available.

+ Details

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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.

+ References

No definition available.

+ Details

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
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-Section S99
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-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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+ Details

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Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Period Type:	instant

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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- Definition

Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1E
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495348-112611

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690

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- Definition

Amount of long-term debt classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
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+ Details

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- Details

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