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Share-Based Compensation - Additional Information (Detail) (USD $)
12 Months Ended 0 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Sep. 10, 2004
Aug. 27, 2008
Sep. 17, 2014
Aug. 19, 1999
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Share based compensation expense $ 708,000us-gaap_AllocatedShareBasedCompensationExpense $ 122,000us-gaap_AllocatedShareBasedCompensationExpense        
Issuance of stock option to purchase stock 6,000,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized          
Common stock reserved for issuance 4,466,233us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance          
Stock option awards vesting period 2 years          
Options granted 1,055,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod 173,354us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod        
Unrecognized compensation cost related to bon-vested 107,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized          
Intrinsic value of options exercised   $ 2,816,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1        
Maximum            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Share-based compensation arrangement by share based payment award options granted contractual term 10 years          
Minimum            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Share-based compensation arrangement by share based payment award options granted contractual term 3 years          
2004 Stock Incentive Plan            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Common stock reserved for issuance     2,500,000us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance
/ us-gaap_PlanNameAxis
= hdsn_TwoThousandAndFourStockIncentivePlanMember
     
Plan expiration date     Sep. 10, 2014      
2008 Stock Incentive Plan            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Common stock reserved for issuance       3,000,000us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance
/ us-gaap_PlanNameAxis
= hdsn_TwoThousandAndEightStockIncentivePlanMember
   
Plan expiration date       Aug. 27, 2018    
Share based compensation arrangement by share based payment award percentage of fair market Person holding more then 10% voting stock       110.00%hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice
/ us-gaap_PlanNameAxis
= hdsn_TwoThousandAndEightStockIncentivePlanMember
   
2014 Stock Incentive Plan            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Common stock reserved for issuance         3,000,000us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance
/ us-gaap_PlanNameAxis
= hdsn_TwoThousandAndFourteenStockIncentivePlanMember
 
Plan expiration date         Sep. 17, 2024  
Share based compensation arrangement by share based payment award percentage of fair market Person holding more then 10% voting stock         110.00%hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice
/ us-gaap_PlanNameAxis
= hdsn_TwoThousandAndFourteenStockIncentivePlanMember
 
2014 Stock Incentive Plan | Maximum            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Expiration period of option awards         10 years  
2014 Stock Incentive Plan | Minimum            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Expiration period of option awards         5 years  
2008 Stock Incentive Plan | Maximum            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Expiration period of option awards       10 years    
2008 Stock Incentive Plan | Minimum            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Expiration period of option awards       5 years    
1997 Employee Stock Option Plan            
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]            
Common stock reserved for issuance           2,000,000us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance
/ us-gaap_EmployeeStockOwnershipPlanESOPDisclosuresByPlanAxis
= hdsn_StockOptionPlanNineteenNinetySevenMember
Plan expiration date           Jun. 11, 2007