Accrued and unpaid interest on unsecured debt.

No definition available.

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Additional line of credit facility borrowing capacity.

+ References

No definition available.

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- Definition

Interest rate under multicurrency facility.

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No definition available.

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- Definition

Line of credit facility covenant compliance debt to capitalization percentage.

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No definition available.

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- Definition

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

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No definition available.

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- Definition

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

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No definition available.

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- Definition

Line of credit facility extended borrowing capacity.

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No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

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

- Definition

Payment on redemption unsecured debt.

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No definition available.

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

- Definition

Premium on redemption of unsecured debt.

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No definition available.

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

- Definition

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

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No definition available.

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- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

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No definition available.

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- Definition

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

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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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- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
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-Subparagraph (b)(2)
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Balance Type:	debit
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- Definition

Amount, after accumulated amortization, of debt premium.

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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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- Definition

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

+ References

No definition available.

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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- Definition

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

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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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Amount of long-term debt classified as other.

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Period Type:	instant

- 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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Period Type:	instant

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Debt - Additional Information (Detail) - USD ($)		12 Months Ended
Debt - Additional Information (Detail) - USD ($)	Aug. 25, 2020	Dec. 31, 2020	Dec. 31, 2019	Oct. 30, 2019
Debt Instrument [Line Items]
Interest rate under multi currency facility		LIBOR, NIBOR or CDOR plus 1.125%
Capitalization ratio, Maximum		60.00%
Capitalization ratio, Actual		28.40%
Funds available under revolving credit facility		$ 2,000,000,000.0
Other debt		70,000,000	$ 9,000,000
Loss on extinguishment of debt		(8,000,000)	(26,000,000)
Outstanding letters of credit under various bilateral letter of credit facilities		446,000,000
Carrying value of Unsecured Senior Notes		1,764,000,000	1,980,000,000
Fair Value, Inputs, Level 2 [Member] \| Unsecured Debt [Member]
Debt Instrument [Line Items]
Fair value of Unsecured Senior Notes		1,833,000,000	$ 1,947,000,000
2.60% unsecured Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Repayment of debt	$ 217,300,000
Senior notes interest rate	2.60%
Payment on redemption	$ 226,000,000
Premium on redemption	7,600,000
Accrued and unpaid interest	1,300,000
Loss on extinguishment of debt	8,200,000
Premium on debt	7,600,000
Non cash charges	$ 600,000
Noncontrolling Interests [Member]
Debt Instrument [Line Items]
Other debt		$ 24,000,000
Canadian Dollar Offered Rate (CDOR) [Member]
Debt Instrument [Line Items]
Variable rate		1.125%
Five Year Unsecured Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility, borrowing capacity				$ 2,000,000,000.0
Credit facility, maturity date		Oct. 30, 2024
Credit facility, extendable borrowing capacity		$ 3,000,000,000.0
Variable rate basis		LIBOR, NIBOR or CDOR plus
Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility, Period		5 years
Five Year Credit Facility [Member]
Debt Instrument [Line Items]
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%