Annual report pursuant to Section 13 and 15(d)

Stock Plans and Stock-Based Compensation - Fair Value Of Option (Detail)

v2.4.1.9
Stock Plans and Stock-Based Compensation - Fair Value Of Option (Detail) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Expected stock price volatility       
Risk free rate of interest       
Maximum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Exercise price   $ 9.21us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
$ 7.84us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Expected stock price volatility   112.70%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
114.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Risk free rate of interest   3.04%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
2.23%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Expected life of options   10 years 10 years
Minimum [Member]      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Exercise price   $ 1.71us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
$ 4.75us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Expected stock price volatility   81.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
87.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Risk free rate of interest   1.01%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
0.16%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Expected life of options   6 years 2 years