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Quarterly Financial Data (Unaudited) (Change in Accounting Estimates) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Change in Accounting Estimate [Line Items]      
Inventory write-down $ 113us-gaap_InventoryWriteDown $ 62us-gaap_InventoryWriteDown $ 53us-gaap_InventoryWriteDown
Excessive Quantities and Obsolescence [Member]      
Change in Accounting Estimate [Line Items]      
Inventory write-down   62us-gaap_InventoryWriteDown
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= wft_ExcessiveQuantitiesandObsolescenceMember		  
Guar Inventory [Member] | Lower of Cost or Market [Member]      
Change in Accounting Estimate [Line Items]      
Inventory write-down     $ 30us-gaap_InventoryWriteDown
/ us-gaap_ChangeInAccountingEstimateByTypeAxis
= wft_LowerofCostorMarketMember
/ us-gaap_PublicUtilitiesInventoryAxis
= wft_GuarInventoryMember