Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Accrued expenses	$ 4.4	$ 3.5
Accounts receivable	1.2	2.4
Net operating loss carryforward	124.0	125.5
Stock-based compensation	3.6	5.2
Intangible assets	8.0evc_DeferredTaxAssetsIntangibleAssets	16.9evc_DeferredTaxAssetsIntangibleAssets
Credits	1.0	1.0
Other	1.1us-gaap_DeferredTaxAssetsOther	0.9us-gaap_DeferredTaxAssetsOther
Deferred Tax Assets Gross	143.3us-gaap_DeferredTaxAssetsGross	155.4us-gaap_DeferredTaxAssetsGross
Valuation allowance	(1.4)	(1.4)
Net deferred tax assets	141.9us-gaap_DeferredTaxAssetsNet	154.0us-gaap_DeferredTaxAssetsNet
Deferred tax liabilities:
Non-long lived intangible assets	(4.8)	(4.9)
Long-lived Intangible assets	(62.2)	(55.4)
Property and equipment	(0.7)	(1.2)
Deferred state taxes	(1.7)evc_DeferredTaxLiabilitiesStateTaxes	(2.5)evc_DeferredTaxLiabilitiesStateTaxes
Net deferred tax liabilities	(69.4)us-gaap_DeferredIncomeTaxLiabilities	(64.0)us-gaap_DeferredIncomeTaxLiabilities
Deferred Assets Liabilities Net	$ 72.5us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 90.0us-gaap_DeferredTaxAssetsLiabilitiesNet

Deferred tax assets intangible assets.

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Deferred tax liabilities long lived intangible assets.

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Deferred tax liabilities non long lived intangible assets.

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Deferred tax liabilities state taxes.

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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The tax effect as of the balance sheet date of the amount of future tax deductions arising from all unused tax credit carryforwards which have been reduced by a valuation allowance.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from accrued liabilities.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the allowance for doubtful accounts.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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