Annual report pursuant to Section 13 and 15(d)

Stock-based Compensation - Summary of Non Vested Awards (Detail)

v2.4.1.9
Stock-based Compensation - Summary of Non Vested Awards (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]      
Number of Shares Underlying Options, Granted 1,118,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross 1,836,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross 1,024,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Restricted Stock      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Restricted Stock, Non-Vested Shares Outstanding at beginning period 100,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember 		   
Number of Shares Underlying Options, Granted 99,468us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember 		   
Restricted Stock, Awards vested (51,600)us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember 		   
Restricted Stock, Non-Vested Shares Outstanding at ending period 147,868us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember 		   
Weighted Average Grant Price, Non-Vested Shares Outstanding at beginning period 5.89us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember 		   
Weighted Average Grant Price, Awards granted 6.98us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember 		   
Weighted Average Grant Price, Awards vested 6.56us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember 		   
Weighted Average Grant Price, Non-Vested Shares Outstanding at ending period 6.39us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember