Annual report pursuant to Section 13 and 15(d)

Debt (Details 4)

v2.4.1.9
Debt (Details 4) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Interest expense on convertible debt  
Accretion of debt discount $ 626us-gaap_AmortizationOfDebtDiscountPremium
Unsecured debt | 1.75% convertible unsecured notes due December 2019  
Interest expense on convertible debt  
Coupon interest 126us-gaap_InterestExpenseDebtExcludingAmortization
/ us-gaap_DebtInstrumentAxis
= env_ConvertibleUnsecured1.75PercentNotesDueDecember2019Member
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
Amortization of issuance costs 38us-gaap_AmortizationOfFinancingCosts
/ us-gaap_DebtInstrumentAxis
= env_ConvertibleUnsecured1.75PercentNotesDueDecember2019Member
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
Accretion of debt discount 203us-gaap_AmortizationOfDebtDiscountPremium
/ us-gaap_DebtInstrumentAxis
= env_ConvertibleUnsecured1.75PercentNotesDueDecember2019Member
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember
Interest Expense, Debt, Total $ 367us-gaap_InterestExpenseDebt
/ us-gaap_DebtInstrumentAxis
= env_ConvertibleUnsecured1.75PercentNotesDueDecember2019Member
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember