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Fair Value Measurements and Other-Than-Temporary Impairments - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 27, 2014
Dec. 28, 2013
Dec. 29, 2012
Disclosure Fair Value Measurements And Other Than Temporary Impairments Additional Information [Abstract]      
Maximum contractual maturity term 18 months    
Proceeds from sales, maturities and calls of available-for-sale investments $ 236.5us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities $ 128.5us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities $ 129.2us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities
Disposal of auction rate securities par value   3.1infn_DisposalOfAuctionRateSecuritiesParValue  
Realized gains on calls $ 0.2us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 $ 0.2us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1