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Common Stock - Additional Information (Detail) $ / shares in Units, $ in Millions				12 Months Ended
	May 28, 2019 $ / shares shares	Feb. 27, 2019 $ / shares shares	Dec. 20, 2017 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) Installment $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 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 \| $				$ 77	$ 76	$ 76
Stock-based compensation expense \| $				130	110	124
Income tax provision recognized \| $				$ 14	$ 16	$ 24
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.
Earlier authorized shares under stock based compensation \| shares				69,400,000
Stock option, Minimum Range \| $ / shares				$ 28.24
Stock option, Maximum Range \| $ / shares				77.99
Weighted average grant-date fair value of options \| $ / shares				$ 9.06	$ 10.01	$ 9.68
Total intrinsic value of options exercised \| $				$ 6	$ 54
Total unrecognized compensation cost related to nonvested stock options \| $				$ 17
Compensation cost not yet recognized, period for recognition				3 years
Total fair value of stock options vested \| $				$ 32	26	$ 70
Cash received from option exercises \| $				7	54	13
Tax benefit (expense) realized for the tax deductions from option exercises \| $				$ (2)	$ 2	$ (2)
Stock options granted				1,493,576	1,610,599	6,961,041
Weighted average exercise price per share of options \| $ / shares				$ 28.72	$ 35.09	$ 36.51
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	$ 8
Shares granted				7,088	14,228
Restricted stock granted fair value \| $ / shares				$ 28.72	$ 35.09
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		2,895,086		3,335,315	2,657,115	1,738,589
Restricted stock granted fair value \| $ / shares		$ 28.72		$ 28.52	$ 35.17	$ 38.74
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		665,740
TSR Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of performance goal				The 2017 and 2018 performance share awards are based entirely on a TSR (total shareholder return) 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 (Oil Service Sector) index for the three-year performance period. The 2019 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 National Oilwell Varco Value Added (“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 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 \| $				$ 102
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				20,200,000
Remaining shares available for future grants under the Plan				10,500,000
2018 Plan [Member] \| Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	65,752
Restricted stock granted fair value \| $ / shares	$ 21.90