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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Customer
Dec. 31, 2013
Dec. 31, 2012
Summary Of Significant Accounting Policies [Line Items]      
Foreign currency transaction losses $ 2us-gaap_ForeignCurrencyTransactionGainLossRealized $ 2us-gaap_ForeignCurrencyTransactionGainLossRealized $ 3us-gaap_ForeignCurrencyTransactionGainLossRealized
Percentage revenue contribution 20dnow_ConcentrationRiskNumberOfMajorCustomers    
Customer Concentration Risk [Member] | Sales Revenue, Net [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Percentage of revenue 10.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember		    
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Major Customers [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Percentage of revenue 33.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= dnow_MajorCustomersMember