Fixed charge coverage ratio

No definition available.

Name:	hdsn_FixedChargeCoverageRatio
Namespace Prefix:	hdsn_
Data Type:	xbrli:pureItemType
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:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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

No definition available.

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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

+ Details

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

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
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Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Debt - Additional Information (Detail)			9 Months Ended
Debt - Additional Information (Detail)	Apr. 08, 2016 USD ($)	Jul. 01, 2015	Sep. 30, 2017 USD ($)	Feb. 15, 2013 USD ($)	Jun. 22, 2012 USD ($)
Credit facility maximum borrowing				$ 40,000,000	$ 50,000,000
Interest rate description under PNC facility			Interest charges with respect to loans were computed on the actual principal amount of loans outstanding during the month at a rate per annum equal to (A) with respect to Domestic Rate Loans (as defined in the PNC Facility), the sum of the Alternate Base Rate (as defined in the PNC Facility) plus one half of one percent (.50%) and (B) with respect to Eurodollar Rate Loans, the sum of the Eurodollar Rate plus two and one quarter of one percent (2.25%).
Line of Credit Facility, Current Borrowing Capacity			$ 50,000,000
Letters of Credit Outstanding, Amount			$ 130,000
Fifth Amendment [Member]
Line of Credit Facility, Expiration Date	Jun. 30, 2020
Revolving Credit Facility [Member]
Credit facility maximum borrowing				36,000,000	$ 46,000,000
Revolving Credit Facility [Member] \| Fourth Amendment [Member]
Interest rate description under PNC facility			Revolving Interest Rate shall mean an interest rate per annum equal to (a) the sum of the Alternate Base Rate (as defined in the PNC Facility) plus one half of one percent (.50%) with respect to Domestic Rate Loans and (b) the sum of the Eurodollar Rate plus two and one quarter of one percent (2.25%) with respect to the Eurodollar Rate Loans.
Revolving Credit Facility [Member] \| Base Rate [Member]
Debt instrument, description of variable rate basis			Alternate Base Rate plus one half of one percent (.50%)
Revolving Credit Facility [Member] \| Base Rate [Member] \| Fourth Amendment [Member]
Debt instrument, description of variable rate basis			Base Rate (as defined in the PNC Facility) plus one half of one percent (.50%)
Revolving Credit Facility [Member] \| Eurodollar [Member] \| Fourth Amendment [Member]
Debt instrument, description of variable rate basis			Eurodollar Rate plus two and one quarter of one percent (2.25%)
Minimum [Member]
Fixed charge coverage ratio			1.00
Minimum [Member] \| Fifth Amendment [Member]
Credit facility maximum borrowing	$ 40,000,000
Minimum [Member] \| Revolving Credit Facility [Member] \| Fifth Amendment [Member]
Credit facility maximum borrowing	36,000,000
Maximum [Member]
Fixed charge coverage ratio			1.10
Maximum [Member] \| Fifth Amendment [Member]
Credit facility maximum borrowing	50,000,000
Maximum [Member] \| Revolving Credit Facility [Member] \| Fifth Amendment [Member]
Credit facility maximum borrowing	$ 46,000,000
Term Loan [Member]
Credit facility maximum borrowing				$ 4,000,000
Term Loan [Member] \| Eurodollar [Member]
Fixed charge coverage ratio percentage		2.25%