Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Numerator:
Net income attributable to DNOW Inc.	$ 22	$ 21
Less: net income attributable to participating securities	(1)	0
Net income attributable to DNOW Inc. stockholders	$ 21	$ 21
Denominator:
Weighted average basic common shares outstanding	105,976,409	106,445,323
Effect of dilutive securities	767,580	902,398
Weighted average diluted common shares outstanding	106,743,989	107,347,721
Basic	$ 0.2	$ 0.2
Diluted	$ 0.2	$ 0.19

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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Amount of undistributed earnings (loss) allocated to participating securities for the basic earnings (loss) per share or per unit calculation under the two-class method.

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