v2.4.1.9
Investments (Detail) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Schedule Of Trading Securities And Other Trading Assets [Line Items]    
Certificates of deposit and money market funds due within one year $ 420,927dva_CertificatesOfDepositMoneyMarketFundsAndUnitedStatesGovernmentSecurities $ 335,975dva_CertificatesOfDepositMoneyMarketFundsAndUnitedStatesGovernmentSecurities
Investments in mutual funds and common stock 29,068dva_MutualFundInvestmentsAtFairValue 28,123dva_MutualFundInvestmentsAtFairValue
Total investment 449,995us-gaap_Investments 364,098us-gaap_Investments
Short-term investments 422,365us-gaap_ShortTermInvestments 337,399us-gaap_ShortTermInvestments
Long-term investments 27,630us-gaap_OtherLongTermInvestments 26,699us-gaap_OtherLongTermInvestments
Held to maturity    
Schedule Of Trading Securities And Other Trading Assets [Line Items]    
Certificates of deposit and money market funds due within one year 420,927dva_CertificatesOfDepositMoneyMarketFundsAndUnitedStatesGovernmentSecurities
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember
335,975dva_CertificatesOfDepositMoneyMarketFundsAndUnitedStatesGovernmentSecurities
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember
Total investment 420,927us-gaap_Investments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember
335,975us-gaap_Investments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember
Short-term investments 420,927us-gaap_ShortTermInvestments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember
335,975us-gaap_ShortTermInvestments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember
Available for sale    
Schedule Of Trading Securities And Other Trading Assets [Line Items]    
Investments in mutual funds and common stock 29,068dva_MutualFundInvestmentsAtFairValue
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_AvailableforsaleSecuritiesMember
28,123dva_MutualFundInvestmentsAtFairValue
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_AvailableforsaleSecuritiesMember
Total investment 29,068us-gaap_Investments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_AvailableforsaleSecuritiesMember
28,123us-gaap_Investments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_AvailableforsaleSecuritiesMember
Short-term investments 1,438us-gaap_ShortTermInvestments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_AvailableforsaleSecuritiesMember
1,424us-gaap_ShortTermInvestments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_AvailableforsaleSecuritiesMember
Long-term investments $ 27,630us-gaap_OtherLongTermInvestments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_AvailableforsaleSecuritiesMember
$ 26,699us-gaap_OtherLongTermInvestments
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= us-gaap_AvailableforsaleSecuritiesMember