Percentage points added to the calculated interest rate dependent on average quarterly undrawn availability.

No definition available.

Name:	hdsn_DebtInstrumentAdditionalPercentagePointsInterest
Namespace Prefix:	hdsn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fixed charge coverage ratio reported during the year.

+ References

No definition available.

+ Details

Name:	hdsn_FixedChargesCoverageRatio
Namespace Prefix:	hdsn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the minimum amount from availability.

+ References

No definition available.

+ Details

Name:	hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidity
Namespace Prefix:	hdsn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the minimum amount to be derived from availability.

+ References

No definition available.

+ Details

Name:	hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability
Namespace Prefix:	hdsn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum amount of shares that can be repurchased by the company over the term of credit facility as per the covenant terms mentioned in the amendment.

+ References

No definition available.

+ Details

Name:	hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchaseOverFacilityTermAmount
Namespace Prefix:	hdsn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum amount of shares that can be repurchased by the company per calendar year after first fiscal year following the current fiscal year as per the covenant's terms mentioned in the amendment.

+ References

No definition available.

+ Details

Name:	hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchasePerCalendarYearAfterYearOneAmount
Namespace Prefix:	hdsn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum amount of shares that can be repurchased by the company per calendar year as per the covenant's terms mentioned in the amendment.

+ References

No definition available.

+ Details

Name:	hdsn_LineOfCreditFacilityCovenantTermsMaximumShareRepurchasePerCalendarYearAmount
Namespace Prefix:	hdsn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The minimum aggregate undrawn term loan availability used to determine percentage of excess cash flow to be used to paydown the loan.

+ References

No definition available.

+ Details

Name:	hdsn_MinimumAggregateUndrawnLoanAvailability
Namespace Prefix:	hdsn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the period for FCCR covenant.

+ References

No definition available.

+ Details

Name:	hdsn_PeriodForFixedChargeCoverageRatio
Namespace Prefix:	hdsn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	hdsn_ShortTermAndLongTermDebtLineItems
Namespace Prefix:	hdsn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-15

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-12

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-14

+ Details

Name:	us-gaap_ProceedsFromLinesOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 15
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-15

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479886/946-10-S99-3

+ Details

Name:	us-gaap_RepaymentsOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_CreditFacilityAxis=hdsn_RevolvingCreditFacilityAmendmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=hdsn_PrimeCommercialLendingRateOfWellsFargoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=hdsn_WellsFargoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=hdsn_FCCRMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=hdsn_SwingLineLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=hdsn_WaiverAndSecondAmendmentToTermLoanCreditAndSecurityAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=hdsn_WaiverAndThirdAmendmentToTermLoanCreditAndSecurityAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=hdsn_FirstInLastOutTrancheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Short-term and Long-term debt (Details) - USD ($) $ in Thousands		9 Months Ended
	Mar. 02, 2022	Sep. 30, 2025	Jun. 23, 2025	Oct. 23, 2024	Jun. 06, 2024
Revolving credit facility Amendment
Short-term and long-term debt
Debt instrument, basis spread on variable rate	1.00%
Additional interest percentage	0.50%
Revolving credit facility Amendment \| SOFR
Short-term and long-term debt
Additional interest percentage	1.00%
Revolving credit facility Amendment \| Minimum \| SOFR
Short-term and long-term debt
Additional interest percentage	2.36%
Revolving credit facility Amendment \| Minimum \| Prime commercial lending rate of Wells Fargo
Short-term and long-term debt
Additional interest percentage	1.25%
Revolving credit facility Amendment \| Maximum \| SOFR
Short-term and long-term debt
Additional interest percentage	2.86%
Revolving credit facility Amendment \| Maximum \| Prime commercial lending rate of Wells Fargo
Short-term and long-term debt
Additional interest percentage	1.75%
Wells Fargo
Short-term and long-term debt
Amount outstanding, letter of credit	$ 900
Wells Fargo \| FCCR
Short-term and long-term debt
Minimum aggregate undrawn loan availability	$ 11,250
Period for FCCR covenant	12 months
Wells Fargo \| Minimum
Short-term and long-term debt
Minimum liquidity requirement	$ 5,000
Minimum amount to be derived from availability	$ 3,000
Wells Fargo \| Minimum \| FCCR
Short-term and long-term debt
Fixed charges coverage ratio	1
Wells Fargo \| Maximum \| FCCR
Short-term and long-term debt
Fixed charges coverage ratio	1
Wells Fargo \| Revolving Credit Facility \| FCCR
Short-term and long-term debt
Period for FCCR covenant	2 months
Wells Fargo \| Revolving Credit Facility \| Maximum
Short-term and long-term debt
Amount borrowed	$ 75,000
Wells Fargo \| Revolving credit facility Amendment
Short-term and long-term debt
Amount borrowed		$ 40,000
Maximum borrowing capacity	$ 75,000
Repayment of debt		$ 0
Wells Fargo \| Revolving credit facility Amendment \| Minimum
Short-term and long-term debt
Additional interest percentage	0.35%
Wells Fargo \| Revolving credit facility Amendment \| Maximum
Short-term and long-term debt
Additional interest percentage	0.75%
Wells Fargo \| Swing line loans
Short-term and long-term debt
Maximum borrowing capacity	$ 9,000
Wells Fargo \| Letters of credit
Short-term and long-term debt
Maximum borrowing capacity	2,000		$ 1,500
Wells Fargo \| First Amendment
Short-term and long-term debt
Stock repurchase amount					$ 5,000
Maximum shares repurchase amount					$ 15,000
Wells Fargo \| Second Amendment
Short-term and long-term debt
Stock repurchase amount				$ 10,000
Maximum shares repurchase amount				25,000
Maximum amount of shares repurchased				$ 5,000
Wells Fargo \| Third Amendment
Short-term and long-term debt
Maximum borrowing capacity	75,000		$ 40,000
Wells Fargo \| FILO Tranche
Short-term and long-term debt
Amount borrowed	$ 15,000