Annual report pursuant to Section 13 and 15(d)

Income Taxes - Change in Valuation Allowance (Details)

v2.4.1.9
Income Taxes - Change in Valuation Allowance (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Deferred Tax Assets, Valuation Allowance [Roll Forward]    
Valuation allowance, beginning balance $ 50,782us-gaap_DeferredTaxAssetsValuationAllowance $ 39,122us-gaap_DeferredTaxAssetsValuationAllowance
Acquired valuation allowance from purchased acquisitions   2,356ent_DeferredTaxesBusinessCombinationsValuationAllowance
Increase in valuation allowance 22,877us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount 9,304us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Valuation allowance, ending balance $ 73,659us-gaap_DeferredTaxAssetsValuationAllowance $ 50,782us-gaap_DeferredTaxAssetsValuationAllowance