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Common Stock - Additional Information (Detail) $ / shares in Units, $ in Millions				12 Months Ended
	May 19, 2021 $ / shares shares	Feb. 22, 2021 $ / shares shares	Dec. 20, 2017 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) Installment $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock, authorized				1,000,000,000	1,000,000,000
Number of preferred stock, authorized				10,000,000
Common stock, par value \| $ / shares				$ 0.01	$ 0.01
Preferred stock, par value \| $ / shares				$ 0.01
Preferred stock, shares issued				0
Preferred stock, shares outstanding				0
Aggregated cash dividends paid \| $				$ 20	$ 19	$ 77
Stock-based compensation expense \| $				78	105	130
Income tax provision recognized \| $				$ 2	$ 3	$ 14
Earlier authorized shares under stock based compensation \| shares				69,400,000
Duration of performance-based restricted stock awards, vested				Options granted under our stock-based compensation plans generally vest over a three-year period starting one year from the date of grant and expire ten years from the date of grant.
Weighted average grant-date fair value of options \| $ / shares				$ 5.75	$ 5.83	$ 9.06
Total intrinsic value of options exercised \| $				$ 0	$ 0
Stock option, Minimum Range \| $ / shares				$ 15.00
Stock option, Maximum Range \| $ / shares				$ 77.99
Total unrecognized compensation cost related to nonvested stock options \| $				$ 11
Compensation cost not yet recognized, period for recognition				3 years
Total fair value of stock options vested \| $				$ 12	18	$ 32
Cash received from option exercises \| $				0	0	7
Tax benefit (expense) realized for the tax deductions from option exercises \| $				$ 0	$ 0	$ (2)
Stock options granted				1,669,511	1,650,262	1,493,576
Weighted average exercise price per share of options \| $ / shares				$ 15.00	$ 20.23	$ 28.72
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights exchange percentage			94.75%
Cash payment of stock appreciation rights \| $			$ 14
Cash paid to settle SARs \| $				$ 0
Compensation cost recognized \| $				$ 0	$ 0	$ 0
Shares granted					7,912
Restricted stock granted fair value \| $ / shares					$ 20.23
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value of options \| $ / shares			$ 8.47
Stock options granted			3,613,707
Weighted average exercise price per share of options \| $ / shares			$ 34.32
Restricted Stock and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
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 date of grant.
Shares granted		2,977,290		3,772,842	3,166,402	3,335,315
Restricted stock granted fair value \| $ / shares		$ 15.00		$ 15.03	$ 19.98	$ 28.52
Number of equal annual vesting installments \| Installment				3
Performance-base restricted stock [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 established goals over a three-year performance period.
Performance-base restricted stock [Member] \| Senior Management Employees [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted		0
Performance-base restricted stock [Member] \| Senior Management Employees [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted		1,434,000
TSR Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of performance goal				The 2019, 2020 and 2021 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 a 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.
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to nonvested stock options \| $				$ 70
Compensation cost not yet recognized, period for recognition				2 years
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%
2018 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares under stock based compensation				42,700,000
Remaining shares available for future grants under the Plan				13,500,000
2018 Plan [Member] \| Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	78,552
Restricted stock granted fair value \| $ / shares	$ 16.50