Additional line of credit facility borrowing capacity.

No definition available.

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Namespace Prefix:	nov_
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- Definition

Debt Instrument Maturity Year.

+ References

No definition available.

+ Details

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- Definition

Interest rate under multicurrency facility.

+ References

No definition available.

+ Details

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- Definition

Line of credit facility covenant compliance debt to capitalization percentage.

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

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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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- Definition

Line of credit facility maturity date.

+ References

No definition available.

+ Details

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- Definition

Line of credit repayment schedule beginning date.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Line of credit repayment schedule ending date.

+ References

No definition available.

+ Details

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

- Definition

Write off Of unamortized discount and debt issuance cost.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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-Publisher FASB
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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.

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt premium.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of accrued but unpaid interest on deposit liabilities.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Balance Type:	credit
Period Type:	instant

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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

- 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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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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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Data Type:	xbrli:monetaryItemType
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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- 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 classified as other.

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest.

+ References

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-SubTopic 10
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-Subparagraph (g)
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- Definition

The excess of the (1) fair value of consideration transferred to the holders of a security in excess of (2) the carrying amount of the security reported on the registrant's balance sheet, which will be deducted from net earnings to derive net earnings available to common shareholders. This amount is generally an adjustment considered in the computation of earnings per share.

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Definition

The cash outflow to repay long-term debt that is not secured by collateral. Excludes repayments of tax exempt unsecured debt.

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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.

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Balance Type:	credit
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Debt - Additional Information (Detail) - USD ($)			6 Months Ended	9 Months Ended
Debt - Additional Information (Detail) - USD ($)	Apr. 09, 2021	Apr. 08, 2021	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
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 1.125%
Capitalization ratio, Maximum				60.00%
Capitalization ratio, Actual				27.70%
Other debt				$ 121,000,000		$ 70,000,000
Redemption of unsecured note				7,000,000	$ 8,000,000
Loss on extinguishment of debt				(7,000,000)	$ (8,000,000)
Outstanding letters of credit under various bilateral letter of credit facilities				441,000,000
Carrying value of Unsecured Senior Notes				1,583,000,000		1,764,000,000
2.60% Unsecured Senior Notes Due December 1, 2022 [Member]
Debt Instrument [Line Items]
Repayment of unsecured note outstanding balance	$ 182,000,000
Senior notes interest rate	2.60%
Redemption of unsecured note	$ 191,000,000
Redemption premium	6,800,000
Accrued and unpaid interest	$ 1,700,000
Loss on extinguishment of debt			$ (7,100,000)
Premium on debt			6,800,000
Write off of unamortized discount and debt issuance cost			$ 300,000
Debt Instrument Maturity Date	2029
Unsecured Debt [Member] \| Fair Value, Inputs, Level 2 [Member]
Debt Instrument [Line Items]
Fair value of Unsecured Senior Notes				1,626,000,000		$ 1,833,000,000
Noncontrolling Interests [Member]
Debt Instrument [Line Items]
Other debt				$ 26,000,000
Canadian Dollar Offered Rate (CDOR) [Member]
Debt Instrument [Line Items]
Variable rate				1.125%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility extended maturity date		Oct. 30, 2025
Line of credit facility current borrowing capacity		$ 2,000,000,000.0
Funds available under revolving credit facility		$ 1,655,000,000
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%
Line of credit repayment schedule beginning date				2022-12
Line of credit repayment schedule ending date				2032-06