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FAIR VALUE MEASUREMENTS - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
1 Months Ended 3 Months Ended
Dec. 31, 2013
Sep. 30, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Asset Impairment Charges   $ 13.5us-gaap_AssetImpairmentCharges
Impairment gain   2.0us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges
Proceeds from Sale of Property, Plant, and Equipment 2.0us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment  
Advanced Academics    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impairment gain   $ 13.5us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges
/ dv_ReportingUnitAxis
= dv_AdvancedAcademicsMember