Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements and Marketable Securities - Marketable Securities with Unrealized Losses (Detail)

v2.4.1.9
Fair Value Measurements and Marketable Securities - Marketable Securities with Unrealized Losses (Detail) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Schedule Of Available For Sale Securities [Line Items]  
Marketable securities, in loss position for less than twelve months, Fair Value $ 29,858us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Marketable securities, in loss position for less than twelve months, Unrealized Loss 17us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Government Securities  
Schedule Of Available For Sale Securities [Line Items]  
Marketable securities, in loss position for less than twelve months, Fair Value 11,722us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_USGovernmentDebtSecuritiesMember
Marketable securities, in loss position for less than twelve months, Unrealized Loss 3us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_USGovernmentDebtSecuritiesMember
Corporate Debt Securities  
Schedule Of Available For Sale Securities [Line Items]  
Marketable securities, in loss position for less than twelve months, Fair Value 18,136us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_CorporateDebtSecuritiesMember
Marketable securities, in loss position for less than twelve months, Unrealized Loss $ 14us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_CorporateDebtSecuritiesMember