Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments - Additional Information (Detail)

v2.4.1.9
Financial Instruments - Additional Information (Detail) (USD $)
3 Months Ended
Mar. 31, 2015
debt_security
Dec. 31, 2014
Debt Instrument [Line Items]    
Number of corporate debt securities 22us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1  
Fair value of debt $ 34,000,000us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue  
Available-for-sale Securities Gross Unrealized Loss Accumulated in Investments 21,000us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax 50,000us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Transfer of securities, Level 1 0us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount  
Transfer of securities, Level 2 0us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount  
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net $ 0us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet  
Minimum [Member]    
Debt Instrument [Line Items]    
Due date of company's long term available for sale securities 1 year  
Maximum [Member]    
Debt Instrument [Line Items]    
Period of unrealized loss position 12 months  
Due date of company's long term available for sale securities 2 years